18140( 3) - 15-Dec-2025 13:48:25 - [ 1] HUBBLE SPACE TELESCOPE OBSERVING PROGRAM 18140 Version: 3 Check-in Time: 15-Dec-2025 13:48:25 STScI Edit Number: 0 Title Flares, Everywhere and All at Once: An NUV/Optical Flare Study of Proxima Centauri ------------------------------------------------------------------------------------ Type Cycle GO 33 ------------------------------------------------------------------------------------ Investigators Contact? PI: Ms. Katherine Bennett The Johns Hopkins University Y CoI: Prof. David K. Sing The Johns Hopkins University N CoI: Dr. Jeff A. Valenti Space Telescope Science Institute N CoI: Dr. Joshua D. Lothringer Space Telescope Science Institute Y CoI: Natalie Allen The Johns Hopkins University N CoI: Prof. Meredith MacGregor The Johns Hopkins University N CoI: Dr. Rachel A. Osten Space Telescope Science Institute N CoI: Zafar Rustamkulov The Johns Hopkins University N ------------------------------------------------------------------------------------ Abstract The impacts of flares remain one of the biggest unknowns in the ability of a close-in rocky M dwarf planet to retain its atmosphere. Specifically, understanding the cumulative flare flux incident on a planet over its geologic lifetime relies on quantifying both the flare rate and flare spectral energy distribution (SED). However, we are often limited to using broadband optical flare studies to extrapolate flare rates to other wavelengths, and it is becoming increasing apparent that UV flare rates extrapolated from optical flares are greatly underestimated. Unfortunately, these studies rely on broadband flares observed across epochs and/or observatories. With HST's WFC3/G280 grism, however, we can for the first time observe NUV-to-optical flare spectra simultaneously. This reveals both the relative NUV and optical rates and the precise NUV SED, which greatly influences planetary atmospheric escape and photochemistry. We target Proxima Centauri, as it is an M-dwarf planet host known to flare frequently, and is also close enough (and therefore bright enough) to be observed in the NUV/optical. We will observe 23 nonconsecutive orbits to observe approximately five flares (95% confidence interval of 2-11 flares). In the case that no flares are detected, we will collect high S/N spectra of an M-dwarf. This is critical for improving M-dwarf models, which are increasingly used to correct for stellar contamination in transmission spectroscopy studies. This is the first study that targets multiwavelength flare observations from a single instrument, and promises to open the door to a new avenue by which to probe flare physics and their impacts on planetary atmospheres. ------------------------------------------------------------------------------------ Observations Description ------------------------ The goal of this program is to measure the UV-optical spectrum of flares occuring on Proxima Centauri. We estimate Proxima Cen flare rates using the U-band photometry from Walker (1981), which gives a reasonable approximation for NUV flare rates. Walker (1981) finds U-band flares of moderate energy (1029 erg s-1) occur once every four hours. We aim to observe for five times this length (20 hours) to account for the stochastic nature of flares, with the goal of observing five flares. Aiming to observe multiple flares is critical to 18140( 3) - 15-Dec-2025 13:48:25 - [ 2] achieve our science goal of characterizing BOTH NUV flare rates and energies. Assuming Poisson statistics, we expect a 95% confidence of catching between 2-11 flares. Observing for 20 science hours translates into about 37 total hours, using the estimated orbital visibility of 52 minutes from APT, which in turn translates into 23 orbits. However, these orbits need not be consecutive, which allows the flexibility required for scheduling observations in reduced gyro mode. In the unlikely event that the NUV flare rates are reflective of the optical flare rates, we would still expect to see one flare in 20 hours given the optical flare rates (1.5-2 flares per day, (Davenport et al. 2016, Vida et al. 2019)). Orient ranges are required in order to avoid contamination from nearby stars. We estimate our orient ranges by propogating Proxima Centauri's proper motion to about 2026 and inspect the field for contaminants. Using the HST ETC, we estimate exposure times to be 40 seconds to stay within 70% of saturation; this gives S/N > 30. Short exposure times are very beneficial for flare studies, as you increase the likelihood of catching the peak of the flare. Walker (1981) found flares with energies of about 10e28 erg s-1 peaked in 20-30 seconds and had a total duration (including rise and decay) of about 13 minutes. We should therefore be able to catch the full flare evolution with these short exposure times. We will acquire on-target. We will follow Bennett et al. 2025 and utilize a 2250x590 subarray on the second UVIS detector chip by offseting the y-position target reference system by -50pix. ------------------------------------------------------------------------------------ 18140( 3) - 15-Dec-2025 13:48:25 - [ 3] TARGET LIST Fixed Targets ------------------------------------------------------------------------------------------------------------------------------------ Tar| Target | Target | Target |Coord | Radial | Flux data No | Name | Description | Position |Eqnx | Vel. | ------------------------------------------------------------------------------------------------------------------------------------ 1 NAME-PROXIMA STAR, M V-IV RA=14H29M42.9461S, J2000 V = 11.13 U=14.21, B=12.95 -CENTAURI DEC=-62D40'46.16" Reference Frame: ICRS Extended: NO Comments: This object was generated by the targetselector and retrieved from the SIMBAD database. SIMBAD listed proper motion for this target. When retrieving targets with PM from SIMBAD, APT requests the coordinates be calculated with an epoch of the year 2000. Do not modify this epoch. Always review coordinates using the Target Confirmation tool, which graphically displays the PM. Epoch of Position RA proper motion (seconds of time/yr) DEC Proper Motion (arcsec/yr) Annual Parallax (arcsec) 2000 -0.5493112058390465 0.7694650000000001 0.7680665 ------------------------------------------------------------------------------------------------------------------------------------ 18140( 3) - 15-Dec-2025 13:48:25 - [ 4] Visit: 01 Visit Requirements: ORIENT 0D TO 20 D; ORIENT 50D TO 120 D; ORIENT 180D TO 200 D; ORIENT 230D TO 300 D On Hold Comments: Additional Comments: The optional parameters SIZEAXIS1=2000 and SIZEAXIS2=300 are used for all exposures to minimize the data volume and hence time lost to buffer dumps. This is fine for the data that needs to be obtained because the spectum will occupy only a narrow swath of pixel rows within the field. This also requires the use of optional parameters CENTERAXIS1 and CENTERAXIS2 in order to "steer" the location of the subarray readout so that it is centered on the target spectrum. If we were positioning on chip 1 we could set CENTERAXIS2=TARGET. However, for the field center (nominal "UVIS" aperture) location on chip 2, we cannot center the subarray on the target because this would cause the subarray to extend into the chip gap, so we hardwire CENTERAXIS1=2136 and CENTERAXIS2=1216, which is intended to put the vertical center of the subarray on the zeroth order of the target spectrum. Chip 2 biases are taken at the end of the visit because the grism exposures use custom subarrays, which will not have matching biases from the WFC3 bias calibration program. For each visit we have phase constraints around the event of the planetary transit, both the orbital period of the planet and the phasing needed are placed on the target acq exposure. To avoid any contamination by several dim, nearby stars, we have placed Orient Ranges for the observations to reach our science goals. This results in ~15 transit opportunities for the UVIS observations in the coming months. Exposures ------------------------------------------------------------------------------------------------------------------------------------ Exp | Target | Instr | Oper. | Aper |Spectral|Central| Optional |Num| Time | Special Num | Name | Config | Mode | or FOV |Element |Waveln.| Parameters |Exp| (Total) | Requirements ------------------------------------------------------------------------------------------------------------------------------------ 1 NAME-PROXIM WFC3/UVI ACCUM G280-REF F300X FLASH=20, CENTERAXIS1=2136, 1 19 S (19 POS TARG null, -50; SEQ A-CENTAURI S CENTERAXIS2=1216, S) 1-3 NON-INT SIZEAXIS1=2000, SIZEAXIS2=300 Comments: For the reference image ("filter acq"), saturation in 259 seconds. 19.3 seconds gives SNR of 150. The nominal "UVIS" aperture is ~10" above the chip gap on chip 1; a Y-postarg of about -50" places the target near the center of subarray on chip 2, at an approximate XY position of (2048, 1024). CENTERAXIS1 and CENTERAXIS2 are used to center the subarray readout on the target spectrum, which will be displaced from the direct image of the target, in agreement with programs 16039, 16695, and 17082. We match the subarray size of the science exposures. We use FLASH=20 to meet the nominal count level. 18140( 3) - 15-Dec-2025 13:48:25 - [ 5] Exposures ------------------------------------------------------------------------------------------------------------------------------------ Exp | Target | Instr | Oper. | Aper |Spectral|Central| Optional |Num| Time | Special Num | Name | Config | Mode | or FOV |Element |Waveln.| Parameters |Exp| (Total) | Requirements ------------------------------------------------------------------------------------------------------------------------------------ ------------------------------------------------------------------------------------------------------------------------------------ 2 NAME-PROXIM WFC3/UVI ACCUM UVIS G280 FLASH=16, SIZEAXIS1=2000, 27 38 S (1026 POS TARG null, -50 A-CENTAURI S SIZEAXIS2=300, S) CENTERAXIS1=2136, CENTERAXIS2=1216 Comments: With exposure time of 40 second, we remain below 50% saturation (w/ saturation at 103 seconds) (with a maximum SNR of about 500 at about 7500 Angstrom), while remaining short enough for decent time-resolution of the flaring event. We also add a FLASH of 16, which when combined with the natural background of about 4 e- per exposure will result in >20 e- and better CTE. Nominal "UVIS" aperture is ~10" above the chip gap on chip 1; a Y-postarg of about -50" places the target near the center of subarray on chip 2. SIZEAXIS1=2000 and SIZEAXIS2=300 are used to minimize data volume, while CENTERAXIS1 and CENTERAXIS2 are used to center the subarray readout on the zeroth order of G280 spectrum. These parameters are based upon similar observations obtained successfully in GOs 13574 and 15288 but have been adjusted to better center the zeroth order spectrum on the sub-array (as done successfully for 16039). ------------------------------------------------------------------------------------------------------------------------------------ 3 BIAS WFC3/UVI ACCUM UVIS DEF SIZEAXIS1=2000, SIZEAXIS2=300, 4 0.0 S (0 S CENTERAXIS1=2136, S) CENTERAXIS2=1216 Comments: We set up the bias frames based on previously sucessful program 11934, 16039, and 16086 and are using the same Aperture and subarray size and position as the observations for direct calibration. ------------------------------------------------------------------------------------------------------------------------------------ 18140( 3) - 15-Dec-2025 13:48:25 - [ 6] Sub Exposures ------------------------------------------------------------------------------------------------------------------------------------ Target | Exp |Instr | Oper. | Aper |Spectral|Cent.|Primary |Secondary |Iteration |CR-SPLIT |Orbit |Duration Name | Num |Config | Mode | or FOV |Element |Wave.|Pattern Pos |Pattern Pos |Num |Num |Number | ------------------------------------------------------------------------------------------------------------------------------------ Sub Exposures ------------------------------------------------------------------------------------------------------------------------------------ Target | Exp |Instr | Oper. | Aper |Spectral|Cent.|Primary |Secondary |Iteration |CR-SPLIT |Orbit |Duration Name | Num |Config | Mode | or FOV |Element |Wave.|Pattern Pos |Pattern Pos |Num |Num |Number | ------------------------------------------------------------------------------------------------------------------------------------ NAME-PROXIMA-CENTAU 1 WFC3/UVI ACCUM G280-REF F300X none none none none 1 N/A RI S NAME-PROXIMA-CENTAU 2 WFC3/UVI ACCUM UVIS G280 none none 1 none 1 N/A RI S NAME-PROXIMA-CENTAU 2 WFC3/UVI ACCUM UVIS G280 none none 2 none 1 N/A RI S NAME-PROXIMA-CENTAU 2 WFC3/UVI ACCUM UVIS G280 none none 3 none 1 N/A RI S NAME-PROXIMA-CENTAU 2 WFC3/UVI ACCUM UVIS G280 none none 4 none 1 N/A RI S NAME-PROXIMA-CENTAU 2 WFC3/UVI ACCUM UVIS G280 none none 5 none 1 N/A RI S NAME-PROXIMA-CENTAU 2 WFC3/UVI ACCUM UVIS G280 none none 6 none 1 N/A RI S NAME-PROXIMA-CENTAU 2 WFC3/UVI ACCUM UVIS G280 none none 7 none 1 N/A RI S NAME-PROXIMA-CENTAU 2 WFC3/UVI ACCUM UVIS G280 none none 8 none 1 N/A RI S NAME-PROXIMA-CENTAU 2 WFC3/UVI ACCUM UVIS G280 none none 9 none 1 N/A RI S NAME-PROXIMA-CENTAU 2 WFC3/UVI ACCUM UVIS G280 none none 10 none 1 N/A RI S NAME-PROXIMA-CENTAU 2 WFC3/UVI ACCUM UVIS G280 none none 11 none 1 N/A RI S NAME-PROXIMA-CENTAU 2 WFC3/UVI ACCUM UVIS G280 none none 12 none 1 N/A RI S NAME-PROXIMA-CENTAU 2 WFC3/UVI ACCUM UVIS G280 none none 13 none 1 N/A RI S NAME-PROXIMA-CENTAU 2 WFC3/UVI ACCUM UVIS G280 none none 14 none 1 N/A RI S NAME-PROXIMA-CENTAU 2 WFC3/UVI ACCUM UVIS G280 none none 15 none 1 N/A RI S NAME-PROXIMA-CENTAU 2 WFC3/UVI ACCUM UVIS G280 none none 16 none 1 N/A RI S NAME-PROXIMA-CENTAU 2 WFC3/UVI ACCUM UVIS G280 none none 17 none 1 N/A RI S NAME-PROXIMA-CENTAU 2 WFC3/UVI ACCUM UVIS G280 none none 18 none 1 N/A RI S NAME-PROXIMA-CENTAU 2 WFC3/UVI ACCUM UVIS G280 none none 19 none 1 N/A RI S NAME-PROXIMA-CENTAU 2 WFC3/UVI ACCUM UVIS G280 none none 20 none 1 N/A RI S 18140( 3) - 15-Dec-2025 13:48:25 - [ 7] Sub Exposures ------------------------------------------------------------------------------------------------------------------------------------ Target | Exp |Instr | Oper. | Aper |Spectral|Cent.|Primary |Secondary |Iteration |CR-SPLIT |Orbit |Duration Name | Num |Config | Mode | or FOV |Element |Wave.|Pattern Pos |Pattern Pos |Num |Num |Number | ------------------------------------------------------------------------------------------------------------------------------------ NAME-PROXIMA-CENTAU 2 WFC3/UVI ACCUM UVIS G280 none none 21 none 1 N/A RI S NAME-PROXIMA-CENTAU 2 WFC3/UVI ACCUM UVIS G280 none none 22 none 1 N/A RI S NAME-PROXIMA-CENTAU 2 WFC3/UVI ACCUM UVIS G280 none none 23 none 1 N/A RI S NAME-PROXIMA-CENTAU 2 WFC3/UVI ACCUM UVIS G280 none none 24 none 1 N/A RI S NAME-PROXIMA-CENTAU 2 WFC3/UVI ACCUM UVIS G280 none none 25 none 1 N/A RI S NAME-PROXIMA-CENTAU 2 WFC3/UVI ACCUM UVIS G280 none none 26 none 1 N/A RI S NAME-PROXIMA-CENTAU 2 WFC3/UVI ACCUM UVIS G280 none none 27 none 1 N/A RI S BIAS 3 WFC3/UVI ACCUM UVIS DEF none none 1 none 1 N/A S BIAS 3 WFC3/UVI ACCUM UVIS DEF none none 2 none 1 N/A S BIAS 3 WFC3/UVI ACCUM UVIS DEF none none 3 none 1 N/A S BIAS 3 WFC3/UVI ACCUM UVIS DEF none none 4 none 1 N/A S 18140( 3) - 15-Dec-2025 13:48:25 - [ 8] Visit: 02 Visit Requirements: ORIENT 0D TO 20 D; ORIENT 50D TO 120 D; ORIENT 180D TO 200 D; ORIENT 230D TO 300 D On Hold Comments: Additional Comments: The optional parameters SIZEAXIS1=2000 and SIZEAXIS2=300 are used for all exposures to minimize the data volume and hence time lost to buffer dumps. This is fine for the data that needs to be obtained because the spectum will occupy only a narrow swath of pixel rows within the field. This also requires the use of optional parameters CENTERAXIS1 and CENTERAXIS2 in order to "steer" the location of the subarray readout so that it is centered on the target spectrum. If we were positioning on chip 1 we could set CENTERAXIS2=TARGET. However, for the field center (nominal "UVIS" aperture) location on chip 2, we cannot center the subarray on the target because this would cause the subarray to extend into the chip gap, so we hardwire CENTERAXIS1=2136 and CENTERAXIS2=1216, which is intended to put the vertical center of the subarray on the zeroth order of the target spectrum. Chip 2 biases are taken at the end of the visit because the grism exposures use custom subarrays, which will not have matching biases from the WFC3 bias calibration program. For each visit we have phase constraints around the event of the planetary transit, both the orbital period of the planet and the phasing needed are placed on the target acq exposure. To avoid any contamination by several dim, nearby stars, we have placed Orient Ranges for the observations to reach our science goals. This results in ~15 transit opportunities for the UVIS observations in the coming months. Exposures ------------------------------------------------------------------------------------------------------------------------------------ Exp | Target | Instr | Oper. | Aper |Spectral|Central| Optional |Num| Time | Special Num | Name | Config | Mode | or FOV |Element |Waveln.| Parameters |Exp| (Total) | Requirements ------------------------------------------------------------------------------------------------------------------------------------ 1 NAME-PROXIM WFC3/UVI ACCUM G280-REF F300X FLASH=20, CENTERAXIS1=2136, 1 19 S (19 POS TARG null, -50; SEQ A-CENTAURI S CENTERAXIS2=1216, S) 1-3 NON-INT SIZEAXIS1=2000, SIZEAXIS2=300 Comments: For the reference image ("filter acq"), saturation in 259 seconds. 19.3 seconds gives SNR of 150. The nominal "UVIS" aperture is ~10" above the chip gap on chip 1; a Y-postarg of about -50" places the target near the center of subarray on chip 2, at an approximate XY position of (2048, 1024). CENTERAXIS1 and CENTERAXIS2 are used to center the subarray readout on the target spectrum, which will be displaced from the direct image of the target, in agreement with programs 16039, 16695, and 17082. We match the subarray size of the science exposures. We use FLASH=20 to meet the nominal count level. 18140( 3) - 15-Dec-2025 13:48:25 - [ 9] Exposures ------------------------------------------------------------------------------------------------------------------------------------ Exp | Target | Instr | Oper. | Aper |Spectral|Central| Optional |Num| Time | Special Num | Name | Config | Mode | or FOV |Element |Waveln.| Parameters |Exp| (Total) | Requirements ------------------------------------------------------------------------------------------------------------------------------------ ------------------------------------------------------------------------------------------------------------------------------------ 2 NAME-PROXIM WFC3/UVI ACCUM UVIS G280 FLASH=16, SIZEAXIS1=2000, 27 38 S (1026 POS TARG null, -50 A-CENTAURI S SIZEAXIS2=300, S) CENTERAXIS1=2136, CENTERAXIS2=1216 Comments: With exposure time of 40 second, we remain below 50% saturation (w/ saturation at 103 seconds) (with a maximum SNR of about 500 at about 7500 Angstrom), while remaining short enough for decent time-resolution of the flaring event. We also add a FLASH of 16, which when combined with the natural background of about 4 e- per exposure will result in >20 e- and better CTE. Nominal "UVIS" aperture is ~10" above the chip gap on chip 1; a Y-postarg of about -50" places the target near the center of subarray on chip 2. SIZEAXIS1=2000 and SIZEAXIS2=300 are used to minimize data volume, while CENTERAXIS1 and CENTERAXIS2 are used to center the subarray readout on the zeroth order of G280 spectrum. These parameters are based upon similar observations obtained successfully in GOs 13574 and 15288 but have been adjusted to better center the zeroth order spectrum on the sub-array (as done successfully for 16039). ------------------------------------------------------------------------------------------------------------------------------------ 3 BIAS WFC3/UVI ACCUM UVIS DEF SIZEAXIS1=2000, SIZEAXIS2=300, 4 0.0 S (0 S CENTERAXIS1=2136, S) CENTERAXIS2=1216 ------------------------------------------------------------------------------------------------------------------------------------ Sub Exposures ------------------------------------------------------------------------------------------------------------------------------------ Target | Exp |Instr | Oper. | Aper |Spectral|Cent.|Primary |Secondary |Iteration |CR-SPLIT |Orbit |Duration Name | Num |Config | Mode | or FOV |Element |Wave.|Pattern Pos |Pattern Pos |Num |Num |Number | ------------------------------------------------------------------------------------------------------------------------------------ NAME-PROXIMA-CENTAU 1 WFC3/UVI ACCUM G280-REF F300X none none none none 1 N/A RI S NAME-PROXIMA-CENTAU 2 WFC3/UVI ACCUM UVIS G280 none none 1 none 1 N/A RI S 18140( 3) - 15-Dec-2025 13:48:25 - [ 10] Sub Exposures ------------------------------------------------------------------------------------------------------------------------------------ Target | Exp |Instr | Oper. | Aper |Spectral|Cent.|Primary |Secondary |Iteration |CR-SPLIT |Orbit |Duration Name | Num |Config | Mode | or FOV |Element |Wave.|Pattern Pos |Pattern Pos |Num |Num |Number | ------------------------------------------------------------------------------------------------------------------------------------ NAME-PROXIMA-CENTAU 2 WFC3/UVI ACCUM UVIS G280 none none 2 none 1 N/A RI S NAME-PROXIMA-CENTAU 2 WFC3/UVI ACCUM UVIS G280 none none 3 none 1 N/A RI S NAME-PROXIMA-CENTAU 2 WFC3/UVI ACCUM UVIS G280 none none 4 none 1 N/A RI S NAME-PROXIMA-CENTAU 2 WFC3/UVI ACCUM UVIS G280 none none 5 none 1 N/A RI S NAME-PROXIMA-CENTAU 2 WFC3/UVI ACCUM UVIS G280 none none 6 none 1 N/A RI S NAME-PROXIMA-CENTAU 2 WFC3/UVI ACCUM UVIS G280 none none 7 none 1 N/A RI S NAME-PROXIMA-CENTAU 2 WFC3/UVI ACCUM UVIS G280 none none 8 none 1 N/A RI S NAME-PROXIMA-CENTAU 2 WFC3/UVI ACCUM UVIS G280 none none 9 none 1 N/A RI S NAME-PROXIMA-CENTAU 2 WFC3/UVI ACCUM UVIS G280 none none 10 none 1 N/A RI S NAME-PROXIMA-CENTAU 2 WFC3/UVI ACCUM UVIS G280 none none 11 none 1 N/A RI S NAME-PROXIMA-CENTAU 2 WFC3/UVI ACCUM UVIS G280 none none 12 none 1 N/A RI S NAME-PROXIMA-CENTAU 2 WFC3/UVI ACCUM UVIS G280 none none 13 none 1 N/A RI S NAME-PROXIMA-CENTAU 2 WFC3/UVI ACCUM UVIS G280 none none 14 none 1 N/A RI S NAME-PROXIMA-CENTAU 2 WFC3/UVI ACCUM UVIS G280 none none 15 none 1 N/A RI S NAME-PROXIMA-CENTAU 2 WFC3/UVI ACCUM UVIS G280 none none 16 none 1 N/A RI S NAME-PROXIMA-CENTAU 2 WFC3/UVI ACCUM UVIS G280 none none 17 none 1 N/A RI S NAME-PROXIMA-CENTAU 2 WFC3/UVI ACCUM UVIS G280 none none 18 none 1 N/A RI S NAME-PROXIMA-CENTAU 2 WFC3/UVI ACCUM UVIS G280 none none 19 none 1 N/A RI S NAME-PROXIMA-CENTAU 2 WFC3/UVI ACCUM UVIS G280 none none 20 none 1 N/A RI S NAME-PROXIMA-CENTAU 2 WFC3/UVI ACCUM UVIS G280 none none 21 none 1 N/A RI S NAME-PROXIMA-CENTAU 2 WFC3/UVI ACCUM UVIS G280 none none 22 none 1 N/A RI S NAME-PROXIMA-CENTAU 2 WFC3/UVI ACCUM UVIS G280 none none 23 none 1 N/A RI S NAME-PROXIMA-CENTAU 2 WFC3/UVI ACCUM UVIS G280 none none 24 none 1 N/A RI S NAME-PROXIMA-CENTAU 2 WFC3/UVI ACCUM UVIS G280 none none 25 none 1 N/A RI S 18140( 3) - 15-Dec-2025 13:48:25 - [ 11] Sub Exposures ------------------------------------------------------------------------------------------------------------------------------------ Target | Exp |Instr | Oper. | Aper |Spectral|Cent.|Primary |Secondary |Iteration |CR-SPLIT |Orbit |Duration Name | Num |Config | Mode | or FOV |Element |Wave.|Pattern Pos |Pattern Pos |Num |Num |Number | ------------------------------------------------------------------------------------------------------------------------------------ NAME-PROXIMA-CENTAU 2 WFC3/UVI ACCUM UVIS G280 none none 26 none 1 N/A RI S NAME-PROXIMA-CENTAU 2 WFC3/UVI ACCUM UVIS G280 none none 27 none 1 N/A RI S BIAS 3 WFC3/UVI ACCUM UVIS DEF none none 1 none 1 N/A S BIAS 3 WFC3/UVI ACCUM UVIS DEF none none 2 none 1 N/A S BIAS 3 WFC3/UVI ACCUM UVIS DEF none none 3 none 1 N/A S BIAS 3 WFC3/UVI ACCUM UVIS DEF none none 4 none 1 N/A S 18140( 3) - 15-Dec-2025 13:48:25 - [ 12] Visit: 03 Visit Requirements: ORIENT 0D TO 20 D; ORIENT 50D TO 120 D; ORIENT 180D TO 200 D; ORIENT 230D TO 300 D On Hold Comments: Additional Comments: The optional parameters SIZEAXIS1=2000 and SIZEAXIS2=300 are used for all exposures to minimize the data volume and hence time lost to buffer dumps. This is fine for the data that needs to be obtained because the spectum will occupy only a narrow swath of pixel rows within the field. This also requires the use of optional parameters CENTERAXIS1 and CENTERAXIS2 in order to "steer" the location of the subarray readout so that it is centered on the target spectrum. If we were positioning on chip 1 we could set CENTERAXIS2=TARGET. However, for the field center (nominal "UVIS" aperture) location on chip 2, we cannot center the subarray on the target because this would cause the subarray to extend into the chip gap, so we hardwire CENTERAXIS1=2136 and CENTERAXIS2=1216, which is intended to put the vertical center of the subarray on the zeroth order of the target spectrum. Chip 2 biases are taken at the end of the visit because the grism exposures use custom subarrays, which will not have matching biases from the WFC3 bias calibration program. For each visit we have phase constraints around the event of the planetary transit, both the orbital period of the planet and the phasing needed are placed on the target acq exposure. To avoid any contamination by several dim, nearby stars, we have placed Orient Ranges for the observations to reach our science goals. This results in ~15 transit opportunities for the UVIS observations in the coming months. Exposures ------------------------------------------------------------------------------------------------------------------------------------ Exp | Target | Instr | Oper. | Aper |Spectral|Central| Optional |Num| Time | Special Num | Name | Config | Mode | or FOV |Element |Waveln.| Parameters |Exp| (Total) | Requirements ------------------------------------------------------------------------------------------------------------------------------------ 1 NAME-PROXIM WFC3/UVI ACCUM G280-REF F300X FLASH=20, CENTERAXIS1=2136, 1 19 S (19 POS TARG null, -50; SEQ A-CENTAURI S CENTERAXIS2=1216, S) 1-3 NON-INT SIZEAXIS1=2000, SIZEAXIS2=300 Comments: For the reference image ("filter acq"), saturation in 259 seconds. 19.3 seconds gives SNR of 150. The nominal "UVIS" aperture is ~10" above the chip gap on chip 1; a Y-postarg of about -50" places the target near the center of subarray on chip 2, at an approximate XY position of (2048, 1024). CENTERAXIS1 and CENTERAXIS2 are used to center the subarray readout on the target spectrum, which will be displaced from the direct image of the target, in agreement with programs 16039, 16695, and 17082. We match the subarray size of the science exposures. We use FLASH=20 to meet the nominal count level. 18140( 3) - 15-Dec-2025 13:48:25 - [ 13] Exposures ------------------------------------------------------------------------------------------------------------------------------------ Exp | Target | Instr | Oper. | Aper |Spectral|Central| Optional |Num| Time | Special Num | Name | Config | Mode | or FOV |Element |Waveln.| Parameters |Exp| (Total) | Requirements ------------------------------------------------------------------------------------------------------------------------------------ ------------------------------------------------------------------------------------------------------------------------------------ 2 NAME-PROXIM WFC3/UVI ACCUM UVIS G280 FLASH=16, SIZEAXIS1=2000, 27 38 S (1026 POS TARG null, -50 A-CENTAURI S SIZEAXIS2=300, S) CENTERAXIS1=2136, CENTERAXIS2=1216 Comments: With exposure time of 40 second, we remain below 50% saturation (w/ saturation at 103 seconds) (with a maximum SNR of about 500 at about 7500 Angstrom), while remaining short enough for decent time-resolution of the flaring event. We also add a FLASH of 16, which when combined with the natural background of about 4 e- per exposure will result in >20 e- and better CTE. Nominal "UVIS" aperture is ~10" above the chip gap on chip 1; a Y-postarg of about -50" places the target near the center of subarray on chip 2. SIZEAXIS1=2000 and SIZEAXIS2=300 are used to minimize data volume, while CENTERAXIS1 and CENTERAXIS2 are used to center the subarray readout on the zeroth order of G280 spectrum. These parameters are based upon similar observations obtained successfully in GOs 13574 and 15288 but have been adjusted to better center the zeroth order spectrum on the sub-array (as done successfully for 16039). ------------------------------------------------------------------------------------------------------------------------------------ 3 BIAS WFC3/UVI ACCUM UVIS DEF SIZEAXIS1=2000, SIZEAXIS2=300, 4 0.0 S (0 S CENTERAXIS1=2136, S) CENTERAXIS2=1216 ------------------------------------------------------------------------------------------------------------------------------------ Sub Exposures ------------------------------------------------------------------------------------------------------------------------------------ Target | Exp |Instr | Oper. | Aper |Spectral|Cent.|Primary |Secondary |Iteration |CR-SPLIT |Orbit |Duration Name | Num |Config | Mode | or FOV |Element |Wave.|Pattern Pos |Pattern Pos |Num |Num |Number | ------------------------------------------------------------------------------------------------------------------------------------ NAME-PROXIMA-CENTAU 1 WFC3/UVI ACCUM G280-REF F300X none none none none 1 N/A RI S NAME-PROXIMA-CENTAU 2 WFC3/UVI ACCUM UVIS G280 none none 1 none 1 N/A RI S 18140( 3) - 15-Dec-2025 13:48:25 - [ 14] Sub Exposures ------------------------------------------------------------------------------------------------------------------------------------ Target | Exp |Instr | Oper. | Aper |Spectral|Cent.|Primary |Secondary |Iteration |CR-SPLIT |Orbit |Duration Name | Num |Config | Mode | or FOV |Element |Wave.|Pattern Pos |Pattern Pos |Num |Num |Number | ------------------------------------------------------------------------------------------------------------------------------------ NAME-PROXIMA-CENTAU 2 WFC3/UVI ACCUM UVIS G280 none none 2 none 1 N/A RI S NAME-PROXIMA-CENTAU 2 WFC3/UVI ACCUM UVIS G280 none none 3 none 1 N/A RI S NAME-PROXIMA-CENTAU 2 WFC3/UVI ACCUM UVIS G280 none none 4 none 1 N/A RI S NAME-PROXIMA-CENTAU 2 WFC3/UVI ACCUM UVIS G280 none none 5 none 1 N/A RI S NAME-PROXIMA-CENTAU 2 WFC3/UVI ACCUM UVIS G280 none none 6 none 1 N/A RI S NAME-PROXIMA-CENTAU 2 WFC3/UVI ACCUM UVIS G280 none none 7 none 1 N/A RI S NAME-PROXIMA-CENTAU 2 WFC3/UVI ACCUM UVIS G280 none none 8 none 1 N/A RI S NAME-PROXIMA-CENTAU 2 WFC3/UVI ACCUM UVIS G280 none none 9 none 1 N/A RI S NAME-PROXIMA-CENTAU 2 WFC3/UVI ACCUM UVIS G280 none none 10 none 1 N/A RI S NAME-PROXIMA-CENTAU 2 WFC3/UVI ACCUM UVIS G280 none none 11 none 1 N/A RI S NAME-PROXIMA-CENTAU 2 WFC3/UVI ACCUM UVIS G280 none none 12 none 1 N/A RI S NAME-PROXIMA-CENTAU 2 WFC3/UVI ACCUM UVIS G280 none none 13 none 1 N/A RI S NAME-PROXIMA-CENTAU 2 WFC3/UVI ACCUM UVIS G280 none none 14 none 1 N/A RI S NAME-PROXIMA-CENTAU 2 WFC3/UVI ACCUM UVIS G280 none none 15 none 1 N/A RI S NAME-PROXIMA-CENTAU 2 WFC3/UVI ACCUM UVIS G280 none none 16 none 1 N/A RI S NAME-PROXIMA-CENTAU 2 WFC3/UVI ACCUM UVIS G280 none none 17 none 1 N/A RI S NAME-PROXIMA-CENTAU 2 WFC3/UVI ACCUM UVIS G280 none none 18 none 1 N/A RI S NAME-PROXIMA-CENTAU 2 WFC3/UVI ACCUM UVIS G280 none none 19 none 1 N/A RI S NAME-PROXIMA-CENTAU 2 WFC3/UVI ACCUM UVIS G280 none none 20 none 1 N/A RI S NAME-PROXIMA-CENTAU 2 WFC3/UVI ACCUM UVIS G280 none none 21 none 1 N/A RI S NAME-PROXIMA-CENTAU 2 WFC3/UVI ACCUM UVIS G280 none none 22 none 1 N/A RI S NAME-PROXIMA-CENTAU 2 WFC3/UVI ACCUM UVIS G280 none none 23 none 1 N/A RI S NAME-PROXIMA-CENTAU 2 WFC3/UVI ACCUM UVIS G280 none none 24 none 1 N/A RI S NAME-PROXIMA-CENTAU 2 WFC3/UVI ACCUM UVIS G280 none none 25 none 1 N/A RI S 18140( 3) - 15-Dec-2025 13:48:25 - [ 15] Sub Exposures ------------------------------------------------------------------------------------------------------------------------------------ Target | Exp |Instr | Oper. | Aper |Spectral|Cent.|Primary |Secondary |Iteration |CR-SPLIT |Orbit |Duration Name | Num |Config | Mode | or FOV |Element |Wave.|Pattern Pos |Pattern Pos |Num |Num |Number | ------------------------------------------------------------------------------------------------------------------------------------ NAME-PROXIMA-CENTAU 2 WFC3/UVI ACCUM UVIS G280 none none 26 none 1 N/A RI S NAME-PROXIMA-CENTAU 2 WFC3/UVI ACCUM UVIS G280 none none 27 none 1 N/A RI S BIAS 3 WFC3/UVI ACCUM UVIS DEF none none 1 none 1 N/A S BIAS 3 WFC3/UVI ACCUM UVIS DEF none none 2 none 1 N/A S BIAS 3 WFC3/UVI ACCUM UVIS DEF none none 3 none 1 N/A S BIAS 3 WFC3/UVI ACCUM UVIS DEF none none 4 none 1 N/A S 18140( 3) - 15-Dec-2025 13:48:25 - [ 16] Visit: 04 Visit Requirements: ORIENT 0D TO 20 D; ORIENT 50D TO 120 D; ORIENT 180D TO 200 D; ORIENT 230D TO 300 D On Hold Comments: Additional Comments: The optional parameters SIZEAXIS1=2000 and SIZEAXIS2=300 are used for all exposures to minimize the data volume and hence time lost to buffer dumps. This is fine for the data that needs to be obtained because the spectum will occupy only a narrow swath of pixel rows within the field. This also requires the use of optional parameters CENTERAXIS1 and CENTERAXIS2 in order to "steer" the location of the subarray readout so that it is centered on the target spectrum. If we were positioning on chip 1 we could set CENTERAXIS2=TARGET. However, for the field center (nominal "UVIS" aperture) location on chip 2, we cannot center the subarray on the target because this would cause the subarray to extend into the chip gap, so we hardwire CENTERAXIS1=2136 and CENTERAXIS2=1216, which is intended to put the vertical center of the subarray on the zeroth order of the target spectrum. Chip 2 biases are taken at the end of the visit because the grism exposures use custom subarrays, which will not have matching biases from the WFC3 bias calibration program. For each visit we have phase constraints around the event of the planetary transit, both the orbital period of the planet and the phasing needed are placed on the target acq exposure. To avoid any contamination by several dim, nearby stars, we have placed Orient Ranges for the observations to reach our science goals. This results in ~15 transit opportunities for the UVIS observations in the coming months. Exposures ------------------------------------------------------------------------------------------------------------------------------------ Exp | Target | Instr | Oper. | Aper |Spectral|Central| Optional |Num| Time | Special Num | Name | Config | Mode | or FOV |Element |Waveln.| Parameters |Exp| (Total) | Requirements ------------------------------------------------------------------------------------------------------------------------------------ 1 NAME-PROXIM WFC3/UVI ACCUM G280-REF F300X FLASH=20, CENTERAXIS1=2136, 1 19 S (19 POS TARG null, -50; SEQ A-CENTAURI S CENTERAXIS2=1216, S) 1-3 NON-INT SIZEAXIS1=2000, SIZEAXIS2=300 Comments: For the reference image ("filter acq"), saturation in 259 seconds. 19.3 seconds gives SNR of 150. The nominal "UVIS" aperture is ~10" above the chip gap on chip 1; a Y-postarg of about -50" places the target near the center of subarray on chip 2, at an approximate XY position of (2048, 1024). CENTERAXIS1 and CENTERAXIS2 are used to center the subarray readout on the target spectrum, which will be displaced from the direct image of the target, in agreement with programs 16039, 16695, and 17082. We match the subarray size of the science exposures. We use FLASH=20 to meet the nominal count level. 18140( 3) - 15-Dec-2025 13:48:25 - [ 17] Exposures ------------------------------------------------------------------------------------------------------------------------------------ Exp | Target | Instr | Oper. | Aper |Spectral|Central| Optional |Num| Time | Special Num | Name | Config | Mode | or FOV |Element |Waveln.| Parameters |Exp| (Total) | Requirements ------------------------------------------------------------------------------------------------------------------------------------ ------------------------------------------------------------------------------------------------------------------------------------ 2 NAME-PROXIM WFC3/UVI ACCUM UVIS G280 FLASH=16, SIZEAXIS1=2000, 27 38 S (1026 POS TARG null, -50 A-CENTAURI S SIZEAXIS2=300, S) CENTERAXIS1=2136, CENTERAXIS2=1216 Comments: With exposure time of 40 second, we remain below 50% saturation (w/ saturation at 103 seconds) (with a maximum SNR of about 500 at about 7500 Angstrom), while remaining short enough for decent time-resolution of the flaring event. We also add a FLASH of 16, which when combined with the natural background of about 4 e- per exposure will result in >20 e- and better CTE. Nominal "UVIS" aperture is ~10" above the chip gap on chip 1; a Y-postarg of about -50" places the target near the center of subarray on chip 2. SIZEAXIS1=2000 and SIZEAXIS2=300 are used to minimize data volume, while CENTERAXIS1 and CENTERAXIS2 are used to center the subarray readout on the zeroth order of G280 spectrum. These parameters are based upon similar observations obtained successfully in GOs 13574 and 15288 but have been adjusted to better center the zeroth order spectrum on the sub-array (as done successfully for 16039). ------------------------------------------------------------------------------------------------------------------------------------ 3 BIAS WFC3/UVI ACCUM UVIS DEF SIZEAXIS1=2000, SIZEAXIS2=300, 4 0.0 S (0 S CENTERAXIS1=2136, S) CENTERAXIS2=1216 ------------------------------------------------------------------------------------------------------------------------------------ Sub Exposures ------------------------------------------------------------------------------------------------------------------------------------ Target | Exp |Instr | Oper. | Aper |Spectral|Cent.|Primary |Secondary |Iteration |CR-SPLIT |Orbit |Duration Name | Num |Config | Mode | or FOV |Element |Wave.|Pattern Pos |Pattern Pos |Num |Num |Number | ------------------------------------------------------------------------------------------------------------------------------------ NAME-PROXIMA-CENTAU 1 WFC3/UVI ACCUM G280-REF F300X none none none none 1 N/A RI S NAME-PROXIMA-CENTAU 2 WFC3/UVI ACCUM UVIS G280 none none 1 none 1 N/A RI S 18140( 3) - 15-Dec-2025 13:48:25 - [ 18] Sub Exposures ------------------------------------------------------------------------------------------------------------------------------------ Target | Exp |Instr | Oper. | Aper |Spectral|Cent.|Primary |Secondary |Iteration |CR-SPLIT |Orbit |Duration Name | Num |Config | Mode | or FOV |Element |Wave.|Pattern Pos |Pattern Pos |Num |Num |Number | ------------------------------------------------------------------------------------------------------------------------------------ NAME-PROXIMA-CENTAU 2 WFC3/UVI ACCUM UVIS G280 none none 2 none 1 N/A RI S NAME-PROXIMA-CENTAU 2 WFC3/UVI ACCUM UVIS G280 none none 3 none 1 N/A RI S NAME-PROXIMA-CENTAU 2 WFC3/UVI ACCUM UVIS G280 none none 4 none 1 N/A RI S NAME-PROXIMA-CENTAU 2 WFC3/UVI ACCUM UVIS G280 none none 5 none 1 N/A RI S NAME-PROXIMA-CENTAU 2 WFC3/UVI ACCUM UVIS G280 none none 6 none 1 N/A RI S NAME-PROXIMA-CENTAU 2 WFC3/UVI ACCUM UVIS G280 none none 7 none 1 N/A RI S NAME-PROXIMA-CENTAU 2 WFC3/UVI ACCUM UVIS G280 none none 8 none 1 N/A RI S NAME-PROXIMA-CENTAU 2 WFC3/UVI ACCUM UVIS G280 none none 9 none 1 N/A RI S NAME-PROXIMA-CENTAU 2 WFC3/UVI ACCUM UVIS G280 none none 10 none 1 N/A RI S NAME-PROXIMA-CENTAU 2 WFC3/UVI ACCUM UVIS G280 none none 11 none 1 N/A RI S NAME-PROXIMA-CENTAU 2 WFC3/UVI ACCUM UVIS G280 none none 12 none 1 N/A RI S NAME-PROXIMA-CENTAU 2 WFC3/UVI ACCUM UVIS G280 none none 13 none 1 N/A RI S NAME-PROXIMA-CENTAU 2 WFC3/UVI ACCUM UVIS G280 none none 14 none 1 N/A RI S NAME-PROXIMA-CENTAU 2 WFC3/UVI ACCUM UVIS G280 none none 15 none 1 N/A RI S NAME-PROXIMA-CENTAU 2 WFC3/UVI ACCUM UVIS G280 none none 16 none 1 N/A RI S NAME-PROXIMA-CENTAU 2 WFC3/UVI ACCUM UVIS G280 none none 17 none 1 N/A RI S NAME-PROXIMA-CENTAU 2 WFC3/UVI ACCUM UVIS G280 none none 18 none 1 N/A RI S NAME-PROXIMA-CENTAU 2 WFC3/UVI ACCUM UVIS G280 none none 19 none 1 N/A RI S NAME-PROXIMA-CENTAU 2 WFC3/UVI ACCUM UVIS G280 none none 20 none 1 N/A RI S NAME-PROXIMA-CENTAU 2 WFC3/UVI ACCUM UVIS G280 none none 21 none 1 N/A RI S NAME-PROXIMA-CENTAU 2 WFC3/UVI ACCUM UVIS G280 none none 22 none 1 N/A RI S NAME-PROXIMA-CENTAU 2 WFC3/UVI ACCUM UVIS G280 none none 23 none 1 N/A RI S NAME-PROXIMA-CENTAU 2 WFC3/UVI ACCUM UVIS G280 none none 24 none 1 N/A RI S NAME-PROXIMA-CENTAU 2 WFC3/UVI ACCUM UVIS G280 none none 25 none 1 N/A RI S 18140( 3) - 15-Dec-2025 13:48:25 - [ 19] Sub Exposures ------------------------------------------------------------------------------------------------------------------------------------ Target | Exp |Instr | Oper. | Aper |Spectral|Cent.|Primary |Secondary |Iteration |CR-SPLIT |Orbit |Duration Name | Num |Config | Mode | or FOV |Element |Wave.|Pattern Pos |Pattern Pos |Num |Num |Number | ------------------------------------------------------------------------------------------------------------------------------------ NAME-PROXIMA-CENTAU 2 WFC3/UVI ACCUM UVIS G280 none none 26 none 1 N/A RI S NAME-PROXIMA-CENTAU 2 WFC3/UVI ACCUM UVIS G280 none none 27 none 1 N/A RI S BIAS 3 WFC3/UVI ACCUM UVIS DEF none none 1 none 1 N/A S BIAS 3 WFC3/UVI ACCUM UVIS DEF none none 2 none 1 N/A S BIAS 3 WFC3/UVI ACCUM UVIS DEF none none 3 none 1 N/A S BIAS 3 WFC3/UVI ACCUM UVIS DEF none none 4 none 1 N/A S 18140( 3) - 15-Dec-2025 13:48:25 - [ 20] Visit: 05 Visit Requirements: ORIENT 0D TO 20 D; ORIENT 50D TO 120 D; ORIENT 180D TO 200 D; ORIENT 230D TO 300 D On Hold Comments: Additional Comments: The optional parameters SIZEAXIS1=2000 and SIZEAXIS2=300 are used for all exposures to minimize the data volume and hence time lost to buffer dumps. This is fine for the data that needs to be obtained because the spectum will occupy only a narrow swath of pixel rows within the field. This also requires the use of optional parameters CENTERAXIS1 and CENTERAXIS2 in order to "steer" the location of the subarray readout so that it is centered on the target spectrum. If we were positioning on chip 1 we could set CENTERAXIS2=TARGET. However, for the field center (nominal "UVIS" aperture) location on chip 2, we cannot center the subarray on the target because this would cause the subarray to extend into the chip gap, so we hardwire CENTERAXIS1=2136 and CENTERAXIS2=1216, which is intended to put the vertical center of the subarray on the zeroth order of the target spectrum. Chip 2 biases are taken at the end of the visit because the grism exposures use custom subarrays, which will not have matching biases from the WFC3 bias calibration program. For each visit we have phase constraints around the event of the planetary transit, both the orbital period of the planet and the phasing needed are placed on the target acq exposure. To avoid any contamination by several dim, nearby stars, we have placed Orient Ranges for the observations to reach our science goals. This results in ~15 transit opportunities for the UVIS observations in the coming months. Exposures ------------------------------------------------------------------------------------------------------------------------------------ Exp | Target | Instr | Oper. | Aper |Spectral|Central| Optional |Num| Time | Special Num | Name | Config | Mode | or FOV |Element |Waveln.| Parameters |Exp| (Total) | Requirements ------------------------------------------------------------------------------------------------------------------------------------ 1 NAME-PROXIM WFC3/UVI ACCUM G280-REF F300X FLASH=20, CENTERAXIS1=2136, 1 19 S (19 POS TARG null, -50; SEQ A-CENTAURI S CENTERAXIS2=1216, S) 1-3 NON-INT SIZEAXIS1=2000, SIZEAXIS2=300 Comments: For the reference image ("filter acq"), saturation in 259 seconds. 19.3 seconds gives SNR of 150. The nominal "UVIS" aperture is ~10" above the chip gap on chip 1; a Y-postarg of about -50" places the target near the center of subarray on chip 2, at an approximate XY position of (2048, 1024). CENTERAXIS1 and CENTERAXIS2 are used to center the subarray readout on the target spectrum, which will be displaced from the direct image of the target, in agreement with programs 16039, 16695, and 17082. We match the subarray size of the science exposures. We use FLASH=20 to meet the nominal count level. 18140( 3) - 15-Dec-2025 13:48:25 - [ 21] Exposures ------------------------------------------------------------------------------------------------------------------------------------ Exp | Target | Instr | Oper. | Aper |Spectral|Central| Optional |Num| Time | Special Num | Name | Config | Mode | or FOV |Element |Waveln.| Parameters |Exp| (Total) | Requirements ------------------------------------------------------------------------------------------------------------------------------------ ------------------------------------------------------------------------------------------------------------------------------------ 2 NAME-PROXIM WFC3/UVI ACCUM UVIS G280 FLASH=16, SIZEAXIS1=2000, 27 38 S (1026 POS TARG null, -50 A-CENTAURI S SIZEAXIS2=300, S) CENTERAXIS1=2136, CENTERAXIS2=1216 Comments: With exposure time of 40 second, we remain below 50% saturation (w/ saturation at 103 seconds) (with a maximum SNR of about 500 at about 7500 Angstrom), while remaining short enough for decent time-resolution of the flaring event. We also add a FLASH of 16, which when combined with the natural background of about 4 e- per exposure will result in >20 e- and better CTE. Nominal "UVIS" aperture is ~10" above the chip gap on chip 1; a Y-postarg of about -50" places the target near the center of subarray on chip 2. SIZEAXIS1=2000 and SIZEAXIS2=300 are used to minimize data volume, while CENTERAXIS1 and CENTERAXIS2 are used to center the subarray readout on the zeroth order of G280 spectrum. These parameters are based upon similar observations obtained successfully in GOs 13574 and 15288 but have been adjusted to better center the zeroth order spectrum on the sub-array (as done successfully for 16039). ------------------------------------------------------------------------------------------------------------------------------------ 3 BIAS WFC3/UVI ACCUM UVIS DEF SIZEAXIS1=2000, SIZEAXIS2=300, 4 0.0 S (0 S CENTERAXIS1=2136, S) CENTERAXIS2=1216 ------------------------------------------------------------------------------------------------------------------------------------ Sub Exposures ------------------------------------------------------------------------------------------------------------------------------------ Target | Exp |Instr | Oper. | Aper |Spectral|Cent.|Primary |Secondary |Iteration |CR-SPLIT |Orbit |Duration Name | Num |Config | Mode | or FOV |Element |Wave.|Pattern Pos |Pattern Pos |Num |Num |Number | ------------------------------------------------------------------------------------------------------------------------------------ NAME-PROXIMA-CENTAU 1 WFC3/UVI ACCUM G280-REF F300X none none none none 1 N/A RI S NAME-PROXIMA-CENTAU 2 WFC3/UVI ACCUM UVIS G280 none none 1 none 1 N/A RI S 18140( 3) - 15-Dec-2025 13:48:25 - [ 22] Sub Exposures ------------------------------------------------------------------------------------------------------------------------------------ Target | Exp |Instr | Oper. | Aper |Spectral|Cent.|Primary |Secondary |Iteration |CR-SPLIT |Orbit |Duration Name | Num |Config | Mode | or FOV |Element |Wave.|Pattern Pos |Pattern Pos |Num |Num |Number | ------------------------------------------------------------------------------------------------------------------------------------ NAME-PROXIMA-CENTAU 2 WFC3/UVI ACCUM UVIS G280 none none 2 none 1 N/A RI S NAME-PROXIMA-CENTAU 2 WFC3/UVI ACCUM UVIS G280 none none 3 none 1 N/A RI S NAME-PROXIMA-CENTAU 2 WFC3/UVI ACCUM UVIS G280 none none 4 none 1 N/A RI S NAME-PROXIMA-CENTAU 2 WFC3/UVI ACCUM UVIS G280 none none 5 none 1 N/A RI S NAME-PROXIMA-CENTAU 2 WFC3/UVI ACCUM UVIS G280 none none 6 none 1 N/A RI S NAME-PROXIMA-CENTAU 2 WFC3/UVI ACCUM UVIS G280 none none 7 none 1 N/A RI S NAME-PROXIMA-CENTAU 2 WFC3/UVI ACCUM UVIS G280 none none 8 none 1 N/A RI S NAME-PROXIMA-CENTAU 2 WFC3/UVI ACCUM UVIS G280 none none 9 none 1 N/A RI S NAME-PROXIMA-CENTAU 2 WFC3/UVI ACCUM UVIS G280 none none 10 none 1 N/A RI S NAME-PROXIMA-CENTAU 2 WFC3/UVI ACCUM UVIS G280 none none 11 none 1 N/A RI S NAME-PROXIMA-CENTAU 2 WFC3/UVI ACCUM UVIS G280 none none 12 none 1 N/A RI S NAME-PROXIMA-CENTAU 2 WFC3/UVI ACCUM UVIS G280 none none 13 none 1 N/A RI S NAME-PROXIMA-CENTAU 2 WFC3/UVI ACCUM UVIS G280 none none 14 none 1 N/A RI S NAME-PROXIMA-CENTAU 2 WFC3/UVI ACCUM UVIS G280 none none 15 none 1 N/A RI S NAME-PROXIMA-CENTAU 2 WFC3/UVI ACCUM UVIS G280 none none 16 none 1 N/A RI S NAME-PROXIMA-CENTAU 2 WFC3/UVI ACCUM UVIS G280 none none 17 none 1 N/A RI S NAME-PROXIMA-CENTAU 2 WFC3/UVI ACCUM UVIS G280 none none 18 none 1 N/A RI S NAME-PROXIMA-CENTAU 2 WFC3/UVI ACCUM UVIS G280 none none 19 none 1 N/A RI S NAME-PROXIMA-CENTAU 2 WFC3/UVI ACCUM UVIS G280 none none 20 none 1 N/A RI S NAME-PROXIMA-CENTAU 2 WFC3/UVI ACCUM UVIS G280 none none 21 none 1 N/A RI S NAME-PROXIMA-CENTAU 2 WFC3/UVI ACCUM UVIS G280 none none 22 none 1 N/A RI S NAME-PROXIMA-CENTAU 2 WFC3/UVI ACCUM UVIS G280 none none 23 none 1 N/A RI S NAME-PROXIMA-CENTAU 2 WFC3/UVI ACCUM UVIS G280 none none 24 none 1 N/A RI S NAME-PROXIMA-CENTAU 2 WFC3/UVI ACCUM UVIS G280 none none 25 none 1 N/A RI S 18140( 3) - 15-Dec-2025 13:48:25 - [ 23] Sub Exposures ------------------------------------------------------------------------------------------------------------------------------------ Target | Exp |Instr | Oper. | Aper |Spectral|Cent.|Primary |Secondary |Iteration |CR-SPLIT |Orbit |Duration Name | Num |Config | Mode | or FOV |Element |Wave.|Pattern Pos |Pattern Pos |Num |Num |Number | ------------------------------------------------------------------------------------------------------------------------------------ NAME-PROXIMA-CENTAU 2 WFC3/UVI ACCUM UVIS G280 none none 26 none 1 N/A RI S NAME-PROXIMA-CENTAU 2 WFC3/UVI ACCUM UVIS G280 none none 27 none 1 N/A RI S BIAS 3 WFC3/UVI ACCUM UVIS DEF none none 1 none 1 N/A S BIAS 3 WFC3/UVI ACCUM UVIS DEF none none 2 none 1 N/A S BIAS 3 WFC3/UVI ACCUM UVIS DEF none none 3 none 1 N/A S BIAS 3 WFC3/UVI ACCUM UVIS DEF none none 4 none 1 N/A S 18140( 3) - 15-Dec-2025 13:48:25 - [ 24] Visit: 06 Visit Requirements: ORIENT 0D TO 20 D; ORIENT 50D TO 120 D; ORIENT 180D TO 200 D; ORIENT 230D TO 300 D On Hold Comments: Additional Comments: The optional parameters SIZEAXIS1=2000 and SIZEAXIS2=300 are used for all exposures to minimize the data volume and hence time lost to buffer dumps. This is fine for the data that needs to be obtained because the spectum will occupy only a narrow swath of pixel rows within the field. This also requires the use of optional parameters CENTERAXIS1 and CENTERAXIS2 in order to "steer" the location of the subarray readout so that it is centered on the target spectrum. If we were positioning on chip 1 we could set CENTERAXIS2=TARGET. However, for the field center (nominal "UVIS" aperture) location on chip 2, we cannot center the subarray on the target because this would cause the subarray to extend into the chip gap, so we hardwire CENTERAXIS1=2136 and CENTERAXIS2=1216, which is intended to put the vertical center of the subarray on the zeroth order of the target spectrum. Chip 2 biases are taken at the end of the visit because the grism exposures use custom subarrays, which will not have matching biases from the WFC3 bias calibration program. For each visit we have phase constraints around the event of the planetary transit, both the orbital period of the planet and the phasing needed are placed on the target acq exposure. To avoid any contamination by several dim, nearby stars, we have placed Orient Ranges for the observations to reach our science goals. This results in ~15 transit opportunities for the UVIS observations in the coming months. Exposures ------------------------------------------------------------------------------------------------------------------------------------ Exp | Target | Instr | Oper. | Aper |Spectral|Central| Optional |Num| Time | Special Num | Name | Config | Mode | or FOV |Element |Waveln.| Parameters |Exp| (Total) | Requirements ------------------------------------------------------------------------------------------------------------------------------------ 1 NAME-PROXIM WFC3/UVI ACCUM G280-REF F300X FLASH=20, CENTERAXIS1=2136, 1 19 S (19 POS TARG null, -50; SEQ A-CENTAURI S CENTERAXIS2=1216, S) 1-3 NON-INT SIZEAXIS1=2000, SIZEAXIS2=300 Comments: For the reference image ("filter acq"), saturation in 259 seconds. 19.3 seconds gives SNR of 150. The nominal "UVIS" aperture is ~10" above the chip gap on chip 1; a Y-postarg of about -50" places the target near the center of subarray on chip 2, at an approximate XY position of (2048, 1024). CENTERAXIS1 and CENTERAXIS2 are used to center the subarray readout on the target spectrum, which will be displaced from the direct image of the target, in agreement with programs 16039, 16695, and 17082. We match the subarray size of the science exposures. We use FLASH=20 to meet the nominal count level. 18140( 3) - 15-Dec-2025 13:48:25 - [ 25] Exposures ------------------------------------------------------------------------------------------------------------------------------------ Exp | Target | Instr | Oper. | Aper |Spectral|Central| Optional |Num| Time | Special Num | Name | Config | Mode | or FOV |Element |Waveln.| Parameters |Exp| (Total) | Requirements ------------------------------------------------------------------------------------------------------------------------------------ ------------------------------------------------------------------------------------------------------------------------------------ 2 NAME-PROXIM WFC3/UVI ACCUM UVIS G280 FLASH=16, SIZEAXIS1=2000, 27 38 S (1026 POS TARG null, -50 A-CENTAURI S SIZEAXIS2=300, S) CENTERAXIS1=2136, CENTERAXIS2=1216 Comments: With exposure time of 40 second, we remain below 50% saturation (w/ saturation at 103 seconds) (with a maximum SNR of about 500 at about 7500 Angstrom), while remaining short enough for decent time-resolution of the flaring event. We also add a FLASH of 16, which when combined with the natural background of about 4 e- per exposure will result in >20 e- and better CTE. Nominal "UVIS" aperture is ~10" above the chip gap on chip 1; a Y-postarg of about -50" places the target near the center of subarray on chip 2. SIZEAXIS1=2000 and SIZEAXIS2=300 are used to minimize data volume, while CENTERAXIS1 and CENTERAXIS2 are used to center the subarray readout on the zeroth order of G280 spectrum. These parameters are based upon similar observations obtained successfully in GOs 13574 and 15288 but have been adjusted to better center the zeroth order spectrum on the sub-array (as done successfully for 16039). ------------------------------------------------------------------------------------------------------------------------------------ 3 BIAS WFC3/UVI ACCUM UVIS DEF SIZEAXIS1=2000, SIZEAXIS2=300, 4 0.0 S (0 S CENTERAXIS1=2136, S) CENTERAXIS2=1216 ------------------------------------------------------------------------------------------------------------------------------------ Sub Exposures ------------------------------------------------------------------------------------------------------------------------------------ Target | Exp |Instr | Oper. | Aper |Spectral|Cent.|Primary |Secondary |Iteration |CR-SPLIT |Orbit |Duration Name | Num |Config | Mode | or FOV |Element |Wave.|Pattern Pos |Pattern Pos |Num |Num |Number | ------------------------------------------------------------------------------------------------------------------------------------ NAME-PROXIMA-CENTAU 1 WFC3/UVI ACCUM G280-REF F300X none none none none 1 N/A RI S NAME-PROXIMA-CENTAU 2 WFC3/UVI ACCUM UVIS G280 none none 1 none 1 N/A RI S 18140( 3) - 15-Dec-2025 13:48:25 - [ 26] Sub Exposures ------------------------------------------------------------------------------------------------------------------------------------ Target | Exp |Instr | Oper. | Aper |Spectral|Cent.|Primary |Secondary |Iteration |CR-SPLIT |Orbit |Duration Name | Num |Config | Mode | or FOV |Element |Wave.|Pattern Pos |Pattern Pos |Num |Num |Number | ------------------------------------------------------------------------------------------------------------------------------------ NAME-PROXIMA-CENTAU 2 WFC3/UVI ACCUM UVIS G280 none none 2 none 1 N/A RI S NAME-PROXIMA-CENTAU 2 WFC3/UVI ACCUM UVIS G280 none none 3 none 1 N/A RI S NAME-PROXIMA-CENTAU 2 WFC3/UVI ACCUM UVIS G280 none none 4 none 1 N/A RI S NAME-PROXIMA-CENTAU 2 WFC3/UVI ACCUM UVIS G280 none none 5 none 1 N/A RI S NAME-PROXIMA-CENTAU 2 WFC3/UVI ACCUM UVIS G280 none none 6 none 1 N/A RI S NAME-PROXIMA-CENTAU 2 WFC3/UVI ACCUM UVIS G280 none none 7 none 1 N/A RI S NAME-PROXIMA-CENTAU 2 WFC3/UVI ACCUM UVIS G280 none none 8 none 1 N/A RI S NAME-PROXIMA-CENTAU 2 WFC3/UVI ACCUM UVIS G280 none none 9 none 1 N/A RI S NAME-PROXIMA-CENTAU 2 WFC3/UVI ACCUM UVIS G280 none none 10 none 1 N/A RI S NAME-PROXIMA-CENTAU 2 WFC3/UVI ACCUM UVIS G280 none none 11 none 1 N/A RI S NAME-PROXIMA-CENTAU 2 WFC3/UVI ACCUM UVIS G280 none none 12 none 1 N/A RI S NAME-PROXIMA-CENTAU 2 WFC3/UVI ACCUM UVIS G280 none none 13 none 1 N/A RI S NAME-PROXIMA-CENTAU 2 WFC3/UVI ACCUM UVIS G280 none none 14 none 1 N/A RI S NAME-PROXIMA-CENTAU 2 WFC3/UVI ACCUM UVIS G280 none none 15 none 1 N/A RI S NAME-PROXIMA-CENTAU 2 WFC3/UVI ACCUM UVIS G280 none none 16 none 1 N/A RI S NAME-PROXIMA-CENTAU 2 WFC3/UVI ACCUM UVIS G280 none none 17 none 1 N/A RI S NAME-PROXIMA-CENTAU 2 WFC3/UVI ACCUM UVIS G280 none none 18 none 1 N/A RI S NAME-PROXIMA-CENTAU 2 WFC3/UVI ACCUM UVIS G280 none none 19 none 1 N/A RI S NAME-PROXIMA-CENTAU 2 WFC3/UVI ACCUM UVIS G280 none none 20 none 1 N/A RI S NAME-PROXIMA-CENTAU 2 WFC3/UVI ACCUM UVIS G280 none none 21 none 1 N/A RI S NAME-PROXIMA-CENTAU 2 WFC3/UVI ACCUM UVIS G280 none none 22 none 1 N/A RI S NAME-PROXIMA-CENTAU 2 WFC3/UVI ACCUM UVIS G280 none none 23 none 1 N/A RI S NAME-PROXIMA-CENTAU 2 WFC3/UVI ACCUM UVIS G280 none none 24 none 1 N/A RI S NAME-PROXIMA-CENTAU 2 WFC3/UVI ACCUM UVIS G280 none none 25 none 1 N/A RI S 18140( 3) - 15-Dec-2025 13:48:25 - [ 27] Sub Exposures ------------------------------------------------------------------------------------------------------------------------------------ Target | Exp |Instr | Oper. | Aper |Spectral|Cent.|Primary |Secondary |Iteration |CR-SPLIT |Orbit |Duration Name | Num |Config | Mode | or FOV |Element |Wave.|Pattern Pos |Pattern Pos |Num |Num |Number | ------------------------------------------------------------------------------------------------------------------------------------ NAME-PROXIMA-CENTAU 2 WFC3/UVI ACCUM UVIS G280 none none 26 none 1 N/A RI S NAME-PROXIMA-CENTAU 2 WFC3/UVI ACCUM UVIS G280 none none 27 none 1 N/A RI S BIAS 3 WFC3/UVI ACCUM UVIS DEF none none 1 none 1 N/A S BIAS 3 WFC3/UVI ACCUM UVIS DEF none none 2 none 1 N/A S BIAS 3 WFC3/UVI ACCUM UVIS DEF none none 3 none 1 N/A S BIAS 3 WFC3/UVI ACCUM UVIS DEF none none 4 none 1 N/A S 18140( 3) - 15-Dec-2025 13:48:25 - [ 28] Visit: 07 Visit Requirements: ORIENT 0D TO 20 D; ORIENT 50D TO 120 D; ORIENT 180D TO 200 D; ORIENT 230D TO 300 D On Hold Comments: Additional Comments: The optional parameters SIZEAXIS1=2000 and SIZEAXIS2=300 are used for all exposures to minimize the data volume and hence time lost to buffer dumps. This is fine for the data that needs to be obtained because the spectum will occupy only a narrow swath of pixel rows within the field. This also requires the use of optional parameters CENTERAXIS1 and CENTERAXIS2 in order to "steer" the location of the subarray readout so that it is centered on the target spectrum. If we were positioning on chip 1 we could set CENTERAXIS2=TARGET. However, for the field center (nominal "UVIS" aperture) location on chip 2, we cannot center the subarray on the target because this would cause the subarray to extend into the chip gap, so we hardwire CENTERAXIS1=2136 and CENTERAXIS2=1216, which is intended to put the vertical center of the subarray on the zeroth order of the target spectrum. Chip 2 biases are taken at the end of the visit because the grism exposures use custom subarrays, which will not have matching biases from the WFC3 bias calibration program. For each visit we have phase constraints around the event of the planetary transit, both the orbital period of the planet and the phasing needed are placed on the target acq exposure. To avoid any contamination by several dim, nearby stars, we have placed Orient Ranges for the observations to reach our science goals. This results in ~15 transit opportunities for the UVIS observations in the coming months. Exposures ------------------------------------------------------------------------------------------------------------------------------------ Exp | Target | Instr | Oper. | Aper |Spectral|Central| Optional |Num| Time | Special Num | Name | Config | Mode | or FOV |Element |Waveln.| Parameters |Exp| (Total) | Requirements ------------------------------------------------------------------------------------------------------------------------------------ 1 NAME-PROXIM WFC3/UVI ACCUM G280-REF F300X FLASH=20, CENTERAXIS1=2136, 1 19 S (19 POS TARG null, -50; SEQ A-CENTAURI S CENTERAXIS2=1216, S) 1-3 NON-INT SIZEAXIS1=2000, SIZEAXIS2=300 Comments: For the reference image ("filter acq"), saturation in 259 seconds. 19.3 seconds gives SNR of 150. The nominal "UVIS" aperture is ~10" above the chip gap on chip 1; a Y-postarg of about -50" places the target near the center of subarray on chip 2, at an approximate XY position of (2048, 1024). CENTERAXIS1 and CENTERAXIS2 are used to center the subarray readout on the target spectrum, which will be displaced from the direct image of the target, in agreement with programs 16039, 16695, and 17082. We match the subarray size of the science exposures. We use FLASH=20 to meet the nominal count level. 18140( 3) - 15-Dec-2025 13:48:25 - [ 29] Exposures ------------------------------------------------------------------------------------------------------------------------------------ Exp | Target | Instr | Oper. | Aper |Spectral|Central| Optional |Num| Time | Special Num | Name | Config | Mode | or FOV |Element |Waveln.| Parameters |Exp| (Total) | Requirements ------------------------------------------------------------------------------------------------------------------------------------ ------------------------------------------------------------------------------------------------------------------------------------ 2 NAME-PROXIM WFC3/UVI ACCUM UVIS G280 FLASH=16, SIZEAXIS1=2000, 27 38 S (1026 POS TARG null, -50 A-CENTAURI S SIZEAXIS2=300, S) CENTERAXIS1=2136, CENTERAXIS2=1216 Comments: With exposure time of 40 second, we remain below 50% saturation (w/ saturation at 103 seconds) (with a maximum SNR of about 500 at about 7500 Angstrom), while remaining short enough for decent time-resolution of the flaring event. We also add a FLASH of 16, which when combined with the natural background of about 4 e- per exposure will result in >20 e- and better CTE. Nominal "UVIS" aperture is ~10" above the chip gap on chip 1; a Y-postarg of about -50" places the target near the center of subarray on chip 2. SIZEAXIS1=2000 and SIZEAXIS2=300 are used to minimize data volume, while CENTERAXIS1 and CENTERAXIS2 are used to center the subarray readout on the zeroth order of G280 spectrum. These parameters are based upon similar observations obtained successfully in GOs 13574 and 15288 but have been adjusted to better center the zeroth order spectrum on the sub-array (as done successfully for 16039). ------------------------------------------------------------------------------------------------------------------------------------ 3 BIAS WFC3/UVI ACCUM UVIS DEF SIZEAXIS1=2000, SIZEAXIS2=300, 4 0.0 S (0 S CENTERAXIS1=2136, S) CENTERAXIS2=1216 ------------------------------------------------------------------------------------------------------------------------------------ Sub Exposures ------------------------------------------------------------------------------------------------------------------------------------ Target | Exp |Instr | Oper. | Aper |Spectral|Cent.|Primary |Secondary |Iteration |CR-SPLIT |Orbit |Duration Name | Num |Config | Mode | or FOV |Element |Wave.|Pattern Pos |Pattern Pos |Num |Num |Number | ------------------------------------------------------------------------------------------------------------------------------------ NAME-PROXIMA-CENTAU 1 WFC3/UVI ACCUM G280-REF F300X none none none none 1 N/A RI S NAME-PROXIMA-CENTAU 2 WFC3/UVI ACCUM UVIS G280 none none 1 none 1 N/A RI S 18140( 3) - 15-Dec-2025 13:48:25 - [ 30] Sub Exposures ------------------------------------------------------------------------------------------------------------------------------------ Target | Exp |Instr | Oper. | Aper |Spectral|Cent.|Primary |Secondary |Iteration |CR-SPLIT |Orbit |Duration Name | Num |Config | Mode | or FOV |Element |Wave.|Pattern Pos |Pattern Pos |Num |Num |Number | ------------------------------------------------------------------------------------------------------------------------------------ NAME-PROXIMA-CENTAU 2 WFC3/UVI ACCUM UVIS G280 none none 2 none 1 N/A RI S NAME-PROXIMA-CENTAU 2 WFC3/UVI ACCUM UVIS G280 none none 3 none 1 N/A RI S NAME-PROXIMA-CENTAU 2 WFC3/UVI ACCUM UVIS G280 none none 4 none 1 N/A RI S NAME-PROXIMA-CENTAU 2 WFC3/UVI ACCUM UVIS G280 none none 5 none 1 N/A RI S NAME-PROXIMA-CENTAU 2 WFC3/UVI ACCUM UVIS G280 none none 6 none 1 N/A RI S NAME-PROXIMA-CENTAU 2 WFC3/UVI ACCUM UVIS G280 none none 7 none 1 N/A RI S NAME-PROXIMA-CENTAU 2 WFC3/UVI ACCUM UVIS G280 none none 8 none 1 N/A RI S NAME-PROXIMA-CENTAU 2 WFC3/UVI ACCUM UVIS G280 none none 9 none 1 N/A RI S NAME-PROXIMA-CENTAU 2 WFC3/UVI ACCUM UVIS G280 none none 10 none 1 N/A RI S NAME-PROXIMA-CENTAU 2 WFC3/UVI ACCUM UVIS G280 none none 11 none 1 N/A RI S NAME-PROXIMA-CENTAU 2 WFC3/UVI ACCUM UVIS G280 none none 12 none 1 N/A RI S NAME-PROXIMA-CENTAU 2 WFC3/UVI ACCUM UVIS G280 none none 13 none 1 N/A RI S NAME-PROXIMA-CENTAU 2 WFC3/UVI ACCUM UVIS G280 none none 14 none 1 N/A RI S NAME-PROXIMA-CENTAU 2 WFC3/UVI ACCUM UVIS G280 none none 15 none 1 N/A RI S NAME-PROXIMA-CENTAU 2 WFC3/UVI ACCUM UVIS G280 none none 16 none 1 N/A RI S NAME-PROXIMA-CENTAU 2 WFC3/UVI ACCUM UVIS G280 none none 17 none 1 N/A RI S NAME-PROXIMA-CENTAU 2 WFC3/UVI ACCUM UVIS G280 none none 18 none 1 N/A RI S NAME-PROXIMA-CENTAU 2 WFC3/UVI ACCUM UVIS G280 none none 19 none 1 N/A RI S NAME-PROXIMA-CENTAU 2 WFC3/UVI ACCUM UVIS G280 none none 20 none 1 N/A RI S NAME-PROXIMA-CENTAU 2 WFC3/UVI ACCUM UVIS G280 none none 21 none 1 N/A RI S NAME-PROXIMA-CENTAU 2 WFC3/UVI ACCUM UVIS G280 none none 22 none 1 N/A RI S NAME-PROXIMA-CENTAU 2 WFC3/UVI ACCUM UVIS G280 none none 23 none 1 N/A RI S NAME-PROXIMA-CENTAU 2 WFC3/UVI ACCUM UVIS G280 none none 24 none 1 N/A RI S NAME-PROXIMA-CENTAU 2 WFC3/UVI ACCUM UVIS G280 none none 25 none 1 N/A RI S 18140( 3) - 15-Dec-2025 13:48:25 - [ 31] Sub Exposures ------------------------------------------------------------------------------------------------------------------------------------ Target | Exp |Instr | Oper. | Aper |Spectral|Cent.|Primary |Secondary |Iteration |CR-SPLIT |Orbit |Duration Name | Num |Config | Mode | or FOV |Element |Wave.|Pattern Pos |Pattern Pos |Num |Num |Number | ------------------------------------------------------------------------------------------------------------------------------------ NAME-PROXIMA-CENTAU 2 WFC3/UVI ACCUM UVIS G280 none none 26 none 1 N/A RI S NAME-PROXIMA-CENTAU 2 WFC3/UVI ACCUM UVIS G280 none none 27 none 1 N/A RI S BIAS 3 WFC3/UVI ACCUM UVIS DEF none none 1 none 1 N/A S BIAS 3 WFC3/UVI ACCUM UVIS DEF none none 2 none 1 N/A S BIAS 3 WFC3/UVI ACCUM UVIS DEF none none 3 none 1 N/A S BIAS 3 WFC3/UVI ACCUM UVIS DEF none none 4 none 1 N/A S 18140( 3) - 15-Dec-2025 13:48:25 - [ 32] Visit: 08 Visit Requirements: ORIENT 0D TO 20 D; ORIENT 50D TO 120 D; ORIENT 180D TO 200 D; ORIENT 230D TO 300 D On Hold Comments: Additional Comments: The optional parameters SIZEAXIS1=2000 and SIZEAXIS2=300 are used for all exposures to minimize the data volume and hence time lost to buffer dumps. This is fine for the data that needs to be obtained because the spectum will occupy only a narrow swath of pixel rows within the field. This also requires the use of optional parameters CENTERAXIS1 and CENTERAXIS2 in order to "steer" the location of the subarray readout so that it is centered on the target spectrum. If we were positioning on chip 1 we could set CENTERAXIS2=TARGET. However, for the field center (nominal "UVIS" aperture) location on chip 2, we cannot center the subarray on the target because this would cause the subarray to extend into the chip gap, so we hardwire CENTERAXIS1=2136 and CENTERAXIS2=1216, which is intended to put the vertical center of the subarray on the zeroth order of the target spectrum. Chip 2 biases are taken at the end of the visit because the grism exposures use custom subarrays, which will not have matching biases from the WFC3 bias calibration program. For each visit we have phase constraints around the event of the planetary transit, both the orbital period of the planet and the phasing needed are placed on the target acq exposure. To avoid any contamination by several dim, nearby stars, we have placed Orient Ranges for the observations to reach our science goals. This results in ~15 transit opportunities for the UVIS observations in the coming months. Exposures ------------------------------------------------------------------------------------------------------------------------------------ Exp | Target | Instr | Oper. | Aper |Spectral|Central| Optional |Num| Time | Special Num | Name | Config | Mode | or FOV |Element |Waveln.| Parameters |Exp| (Total) | Requirements ------------------------------------------------------------------------------------------------------------------------------------ 1 NAME-PROXIM WFC3/UVI ACCUM G280-REF F300X FLASH=20, CENTERAXIS1=2136, 1 19 S (19 POS TARG null, -50; SEQ A-CENTAURI S CENTERAXIS2=1216, S) 1-3 NON-INT SIZEAXIS1=2000, SIZEAXIS2=300 Comments: For the reference image ("filter acq"), saturation in 259 seconds. 19.3 seconds gives SNR of 150. The nominal "UVIS" aperture is ~10" above the chip gap on chip 1; a Y-postarg of about -50" places the target near the center of subarray on chip 2, at an approximate XY position of (2048, 1024). CENTERAXIS1 and CENTERAXIS2 are used to center the subarray readout on the target spectrum, which will be displaced from the direct image of the target, in agreement with programs 16039, 16695, and 17082. We match the subarray size of the science exposures. We use FLASH=20 to meet the nominal count level. 18140( 3) - 15-Dec-2025 13:48:25 - [ 33] Exposures ------------------------------------------------------------------------------------------------------------------------------------ Exp | Target | Instr | Oper. | Aper |Spectral|Central| Optional |Num| Time | Special Num | Name | Config | Mode | or FOV |Element |Waveln.| Parameters |Exp| (Total) | Requirements ------------------------------------------------------------------------------------------------------------------------------------ ------------------------------------------------------------------------------------------------------------------------------------ 2 NAME-PROXIM WFC3/UVI ACCUM UVIS G280 FLASH=16, SIZEAXIS1=2000, 27 38 S (1026 POS TARG null, -50 A-CENTAURI S SIZEAXIS2=300, S) CENTERAXIS1=2136, CENTERAXIS2=1216 Comments: With exposure time of 40 second, we remain below 50% saturation (w/ saturation at 103 seconds) (with a maximum SNR of about 500 at about 7500 Angstrom), while remaining short enough for decent time-resolution of the flaring event. We also add a FLASH of 16, which when combined with the natural background of about 4 e- per exposure will result in >20 e- and better CTE. Nominal "UVIS" aperture is ~10" above the chip gap on chip 1; a Y-postarg of about -50" places the target near the center of subarray on chip 2. SIZEAXIS1=2000 and SIZEAXIS2=300 are used to minimize data volume, while CENTERAXIS1 and CENTERAXIS2 are used to center the subarray readout on the zeroth order of G280 spectrum. These parameters are based upon similar observations obtained successfully in GOs 13574 and 15288 but have been adjusted to better center the zeroth order spectrum on the sub-array (as done successfully for 16039). ------------------------------------------------------------------------------------------------------------------------------------ 3 BIAS WFC3/UVI ACCUM UVIS DEF SIZEAXIS1=2000, SIZEAXIS2=300, 4 0.0 S (0 S CENTERAXIS1=2136, S) CENTERAXIS2=1216 ------------------------------------------------------------------------------------------------------------------------------------ Sub Exposures ------------------------------------------------------------------------------------------------------------------------------------ Target | Exp |Instr | Oper. | Aper |Spectral|Cent.|Primary |Secondary |Iteration |CR-SPLIT |Orbit |Duration Name | Num |Config | Mode | or FOV |Element |Wave.|Pattern Pos |Pattern Pos |Num |Num |Number | ------------------------------------------------------------------------------------------------------------------------------------ NAME-PROXIMA-CENTAU 1 WFC3/UVI ACCUM G280-REF F300X none none none none 1 N/A RI S NAME-PROXIMA-CENTAU 2 WFC3/UVI ACCUM UVIS G280 none none 1 none 1 N/A RI S 18140( 3) - 15-Dec-2025 13:48:25 - [ 34] Sub Exposures ------------------------------------------------------------------------------------------------------------------------------------ Target | Exp |Instr | Oper. | Aper |Spectral|Cent.|Primary |Secondary |Iteration |CR-SPLIT |Orbit |Duration Name | Num |Config | Mode | or FOV |Element |Wave.|Pattern Pos |Pattern Pos |Num |Num |Number | ------------------------------------------------------------------------------------------------------------------------------------ NAME-PROXIMA-CENTAU 2 WFC3/UVI ACCUM UVIS G280 none none 2 none 1 N/A RI S NAME-PROXIMA-CENTAU 2 WFC3/UVI ACCUM UVIS G280 none none 3 none 1 N/A RI S NAME-PROXIMA-CENTAU 2 WFC3/UVI ACCUM UVIS G280 none none 4 none 1 N/A RI S NAME-PROXIMA-CENTAU 2 WFC3/UVI ACCUM UVIS G280 none none 5 none 1 N/A RI S NAME-PROXIMA-CENTAU 2 WFC3/UVI ACCUM UVIS G280 none none 6 none 1 N/A RI S NAME-PROXIMA-CENTAU 2 WFC3/UVI ACCUM UVIS G280 none none 7 none 1 N/A RI S NAME-PROXIMA-CENTAU 2 WFC3/UVI ACCUM UVIS G280 none none 8 none 1 N/A RI S NAME-PROXIMA-CENTAU 2 WFC3/UVI ACCUM UVIS G280 none none 9 none 1 N/A RI S NAME-PROXIMA-CENTAU 2 WFC3/UVI ACCUM UVIS G280 none none 10 none 1 N/A RI S NAME-PROXIMA-CENTAU 2 WFC3/UVI ACCUM UVIS G280 none none 11 none 1 N/A RI S NAME-PROXIMA-CENTAU 2 WFC3/UVI ACCUM UVIS G280 none none 12 none 1 N/A RI S NAME-PROXIMA-CENTAU 2 WFC3/UVI ACCUM UVIS G280 none none 13 none 1 N/A RI S NAME-PROXIMA-CENTAU 2 WFC3/UVI ACCUM UVIS G280 none none 14 none 1 N/A RI S NAME-PROXIMA-CENTAU 2 WFC3/UVI ACCUM UVIS G280 none none 15 none 1 N/A RI S NAME-PROXIMA-CENTAU 2 WFC3/UVI ACCUM UVIS G280 none none 16 none 1 N/A RI S NAME-PROXIMA-CENTAU 2 WFC3/UVI ACCUM UVIS G280 none none 17 none 1 N/A RI S NAME-PROXIMA-CENTAU 2 WFC3/UVI ACCUM UVIS G280 none none 18 none 1 N/A RI S NAME-PROXIMA-CENTAU 2 WFC3/UVI ACCUM UVIS G280 none none 19 none 1 N/A RI S NAME-PROXIMA-CENTAU 2 WFC3/UVI ACCUM UVIS G280 none none 20 none 1 N/A RI S NAME-PROXIMA-CENTAU 2 WFC3/UVI ACCUM UVIS G280 none none 21 none 1 N/A RI S NAME-PROXIMA-CENTAU 2 WFC3/UVI ACCUM UVIS G280 none none 22 none 1 N/A RI S NAME-PROXIMA-CENTAU 2 WFC3/UVI ACCUM UVIS G280 none none 23 none 1 N/A RI S NAME-PROXIMA-CENTAU 2 WFC3/UVI ACCUM UVIS G280 none none 24 none 1 N/A RI S NAME-PROXIMA-CENTAU 2 WFC3/UVI ACCUM UVIS G280 none none 25 none 1 N/A RI S 18140( 3) - 15-Dec-2025 13:48:25 - [ 35] Sub Exposures ------------------------------------------------------------------------------------------------------------------------------------ Target | Exp |Instr | Oper. | Aper |Spectral|Cent.|Primary |Secondary |Iteration |CR-SPLIT |Orbit |Duration Name | Num |Config | Mode | or FOV |Element |Wave.|Pattern Pos |Pattern Pos |Num |Num |Number | ------------------------------------------------------------------------------------------------------------------------------------ NAME-PROXIMA-CENTAU 2 WFC3/UVI ACCUM UVIS G280 none none 26 none 1 N/A RI S NAME-PROXIMA-CENTAU 2 WFC3/UVI ACCUM UVIS G280 none none 27 none 1 N/A RI S BIAS 3 WFC3/UVI ACCUM UVIS DEF none none 1 none 1 N/A S BIAS 3 WFC3/UVI ACCUM UVIS DEF none none 2 none 1 N/A S BIAS 3 WFC3/UVI ACCUM UVIS DEF none none 3 none 1 N/A S BIAS 3 WFC3/UVI ACCUM UVIS DEF none none 4 none 1 N/A S 18140( 3) - 15-Dec-2025 13:48:25 - [ 36] Visit: 09 Visit Requirements: ORIENT 0D TO 20 D; ORIENT 50D TO 120 D; ORIENT 180D TO 200 D; ORIENT 230D TO 300 D On Hold Comments: Additional Comments: The optional parameters SIZEAXIS1=2000 and SIZEAXIS2=300 are used for all exposures to minimize the data volume and hence time lost to buffer dumps. This is fine for the data that needs to be obtained because the spectum will occupy only a narrow swath of pixel rows within the field. This also requires the use of optional parameters CENTERAXIS1 and CENTERAXIS2 in order to "steer" the location of the subarray readout so that it is centered on the target spectrum. If we were positioning on chip 1 we could set CENTERAXIS2=TARGET. However, for the field center (nominal "UVIS" aperture) location on chip 2, we cannot center the subarray on the target because this would cause the subarray to extend into the chip gap, so we hardwire CENTERAXIS1=2136 and CENTERAXIS2=1216, which is intended to put the vertical center of the subarray on the zeroth order of the target spectrum. Chip 2 biases are taken at the end of the visit because the grism exposures use custom subarrays, which will not have matching biases from the WFC3 bias calibration program. For each visit we have phase constraints around the event of the planetary transit, both the orbital period of the planet and the phasing needed are placed on the target acq exposure. To avoid any contamination by several dim, nearby stars, we have placed Orient Ranges for the observations to reach our science goals. This results in ~15 transit opportunities for the UVIS observations in the coming months. Exposures ------------------------------------------------------------------------------------------------------------------------------------ Exp | Target | Instr | Oper. | Aper |Spectral|Central| Optional |Num| Time | Special Num | Name | Config | Mode | or FOV |Element |Waveln.| Parameters |Exp| (Total) | Requirements ------------------------------------------------------------------------------------------------------------------------------------ 1 NAME-PROXIM WFC3/UVI ACCUM G280-REF F300X FLASH=20, CENTERAXIS1=2136, 1 19 S (19 POS TARG null, -50; SEQ A-CENTAURI S CENTERAXIS2=1216, S) 1-3 NON-INT SIZEAXIS1=2000, SIZEAXIS2=300 Comments: For the reference image ("filter acq"), saturation in 259 seconds. 19.3 seconds gives SNR of 150. The nominal "UVIS" aperture is ~10" above the chip gap on chip 1; a Y-postarg of about -50" places the target near the center of subarray on chip 2, at an approximate XY position of (2048, 1024). CENTERAXIS1 and CENTERAXIS2 are used to center the subarray readout on the target spectrum, which will be displaced from the direct image of the target, in agreement with programs 16039, 16695, and 17082. We match the subarray size of the science exposures. We use FLASH=20 to meet the nominal count level. 18140( 3) - 15-Dec-2025 13:48:25 - [ 37] Exposures ------------------------------------------------------------------------------------------------------------------------------------ Exp | Target | Instr | Oper. | Aper |Spectral|Central| Optional |Num| Time | Special Num | Name | Config | Mode | or FOV |Element |Waveln.| Parameters |Exp| (Total) | Requirements ------------------------------------------------------------------------------------------------------------------------------------ ------------------------------------------------------------------------------------------------------------------------------------ 2 NAME-PROXIM WFC3/UVI ACCUM UVIS G280 FLASH=16, SIZEAXIS1=2000, 27 38 S (1026 POS TARG null, -50 A-CENTAURI S SIZEAXIS2=300, S) CENTERAXIS1=2136, CENTERAXIS2=1216 Comments: With exposure time of 40 second, we remain below 50% saturation (w/ saturation at 103 seconds) (with a maximum SNR of about 500 at about 7500 Angstrom), while remaining short enough for decent time-resolution of the flaring event. We also add a FLASH of 16, which when combined with the natural background of about 4 e- per exposure will result in >20 e- and better CTE. Nominal "UVIS" aperture is ~10" above the chip gap on chip 1; a Y-postarg of about -50" places the target near the center of subarray on chip 2. SIZEAXIS1=2000 and SIZEAXIS2=300 are used to minimize data volume, while CENTERAXIS1 and CENTERAXIS2 are used to center the subarray readout on the zeroth order of G280 spectrum. These parameters are based upon similar observations obtained successfully in GOs 13574 and 15288 but have been adjusted to better center the zeroth order spectrum on the sub-array (as done successfully for 16039). ------------------------------------------------------------------------------------------------------------------------------------ 3 BIAS WFC3/UVI ACCUM UVIS DEF SIZEAXIS1=2000, SIZEAXIS2=300, 4 0.0 S (0 S CENTERAXIS1=2136, S) CENTERAXIS2=1216 ------------------------------------------------------------------------------------------------------------------------------------ Sub Exposures ------------------------------------------------------------------------------------------------------------------------------------ Target | Exp |Instr | Oper. | Aper |Spectral|Cent.|Primary |Secondary |Iteration |CR-SPLIT |Orbit |Duration Name | Num |Config | Mode | or FOV |Element |Wave.|Pattern Pos |Pattern Pos |Num |Num |Number | ------------------------------------------------------------------------------------------------------------------------------------ NAME-PROXIMA-CENTAU 1 WFC3/UVI ACCUM G280-REF F300X none none none none 1 N/A RI S NAME-PROXIMA-CENTAU 2 WFC3/UVI ACCUM UVIS G280 none none 1 none 1 N/A RI S 18140( 3) - 15-Dec-2025 13:48:25 - [ 38] Sub Exposures ------------------------------------------------------------------------------------------------------------------------------------ Target | Exp |Instr | Oper. | Aper |Spectral|Cent.|Primary |Secondary |Iteration |CR-SPLIT |Orbit |Duration Name | Num |Config | Mode | or FOV |Element |Wave.|Pattern Pos |Pattern Pos |Num |Num |Number | ------------------------------------------------------------------------------------------------------------------------------------ NAME-PROXIMA-CENTAU 2 WFC3/UVI ACCUM UVIS G280 none none 2 none 1 N/A RI S NAME-PROXIMA-CENTAU 2 WFC3/UVI ACCUM UVIS G280 none none 3 none 1 N/A RI S NAME-PROXIMA-CENTAU 2 WFC3/UVI ACCUM UVIS G280 none none 4 none 1 N/A RI S NAME-PROXIMA-CENTAU 2 WFC3/UVI ACCUM UVIS G280 none none 5 none 1 N/A RI S NAME-PROXIMA-CENTAU 2 WFC3/UVI ACCUM UVIS G280 none none 6 none 1 N/A RI S NAME-PROXIMA-CENTAU 2 WFC3/UVI ACCUM UVIS G280 none none 7 none 1 N/A RI S NAME-PROXIMA-CENTAU 2 WFC3/UVI ACCUM UVIS G280 none none 8 none 1 N/A RI S NAME-PROXIMA-CENTAU 2 WFC3/UVI ACCUM UVIS G280 none none 9 none 1 N/A RI S NAME-PROXIMA-CENTAU 2 WFC3/UVI ACCUM UVIS G280 none none 10 none 1 N/A RI S NAME-PROXIMA-CENTAU 2 WFC3/UVI ACCUM UVIS G280 none none 11 none 1 N/A RI S NAME-PROXIMA-CENTAU 2 WFC3/UVI ACCUM UVIS G280 none none 12 none 1 N/A RI S NAME-PROXIMA-CENTAU 2 WFC3/UVI ACCUM UVIS G280 none none 13 none 1 N/A RI S NAME-PROXIMA-CENTAU 2 WFC3/UVI ACCUM UVIS G280 none none 14 none 1 N/A RI S NAME-PROXIMA-CENTAU 2 WFC3/UVI ACCUM UVIS G280 none none 15 none 1 N/A RI S NAME-PROXIMA-CENTAU 2 WFC3/UVI ACCUM UVIS G280 none none 16 none 1 N/A RI S NAME-PROXIMA-CENTAU 2 WFC3/UVI ACCUM UVIS G280 none none 17 none 1 N/A RI S NAME-PROXIMA-CENTAU 2 WFC3/UVI ACCUM UVIS G280 none none 18 none 1 N/A RI S NAME-PROXIMA-CENTAU 2 WFC3/UVI ACCUM UVIS G280 none none 19 none 1 N/A RI S NAME-PROXIMA-CENTAU 2 WFC3/UVI ACCUM UVIS G280 none none 20 none 1 N/A RI S NAME-PROXIMA-CENTAU 2 WFC3/UVI ACCUM UVIS G280 none none 21 none 1 N/A RI S NAME-PROXIMA-CENTAU 2 WFC3/UVI ACCUM UVIS G280 none none 22 none 1 N/A RI S NAME-PROXIMA-CENTAU 2 WFC3/UVI ACCUM UVIS G280 none none 23 none 1 N/A RI S NAME-PROXIMA-CENTAU 2 WFC3/UVI ACCUM UVIS G280 none none 24 none 1 N/A RI S NAME-PROXIMA-CENTAU 2 WFC3/UVI ACCUM UVIS G280 none none 25 none 1 N/A RI S 18140( 3) - 15-Dec-2025 13:48:25 - [ 39] Sub Exposures ------------------------------------------------------------------------------------------------------------------------------------ Target | Exp |Instr | Oper. | Aper |Spectral|Cent.|Primary |Secondary |Iteration |CR-SPLIT |Orbit |Duration Name | Num |Config | Mode | or FOV |Element |Wave.|Pattern Pos |Pattern Pos |Num |Num |Number | ------------------------------------------------------------------------------------------------------------------------------------ NAME-PROXIMA-CENTAU 2 WFC3/UVI ACCUM UVIS G280 none none 26 none 1 N/A RI S NAME-PROXIMA-CENTAU 2 WFC3/UVI ACCUM UVIS G280 none none 27 none 1 N/A RI S BIAS 3 WFC3/UVI ACCUM UVIS DEF none none 1 none 1 N/A S BIAS 3 WFC3/UVI ACCUM UVIS DEF none none 2 none 1 N/A S BIAS 3 WFC3/UVI ACCUM UVIS DEF none none 3 none 1 N/A S BIAS 3 WFC3/UVI ACCUM UVIS DEF none none 4 none 1 N/A S 18140( 3) - 15-Dec-2025 13:48:25 - [ 40] Visit: 10 Visit Requirements: ORIENT 0D TO 20 D; ORIENT 50D TO 120 D; ORIENT 180D TO 200 D; ORIENT 230D TO 300 D On Hold Comments: Additional Comments: The optional parameters SIZEAXIS1=2000 and SIZEAXIS2=300 are used for all exposures to minimize the data volume and hence time lost to buffer dumps. This is fine for the data that needs to be obtained because the spectum will occupy only a narrow swath of pixel rows within the field. This also requires the use of optional parameters CENTERAXIS1 and CENTERAXIS2 in order to "steer" the location of the subarray readout so that it is centered on the target spectrum. If we were positioning on chip 1 we could set CENTERAXIS2=TARGET. However, for the field center (nominal "UVIS" aperture) location on chip 2, we cannot center the subarray on the target because this would cause the subarray to extend into the chip gap, so we hardwire CENTERAXIS1=2136 and CENTERAXIS2=1216, which is intended to put the vertical center of the subarray on the zeroth order of the target spectrum. Chip 2 biases are taken at the end of the visit because the grism exposures use custom subarrays, which will not have matching biases from the WFC3 bias calibration program. For each visit we have phase constraints around the event of the planetary transit, both the orbital period of the planet and the phasing needed are placed on the target acq exposure. To avoid any contamination by several dim, nearby stars, we have placed Orient Ranges for the observations to reach our science goals. This results in ~15 transit opportunities for the UVIS observations in the coming months. Exposures ------------------------------------------------------------------------------------------------------------------------------------ Exp | Target | Instr | Oper. | Aper |Spectral|Central| Optional |Num| Time | Special Num | Name | Config | Mode | or FOV |Element |Waveln.| Parameters |Exp| (Total) | Requirements ------------------------------------------------------------------------------------------------------------------------------------ 1 NAME-PROXIM WFC3/UVI ACCUM G280-REF F300X FLASH=20, CENTERAXIS1=2136, 1 19 S (19 POS TARG null, -50; SEQ A-CENTAURI S CENTERAXIS2=1216, S) 1-3 NON-INT SIZEAXIS1=2000, SIZEAXIS2=300 Comments: For the reference image ("filter acq"), saturation in 259 seconds. 19.3 seconds gives SNR of 150. The nominal "UVIS" aperture is ~10" above the chip gap on chip 1; a Y-postarg of about -50" places the target near the center of subarray on chip 2, at an approximate XY position of (2048, 1024). CENTERAXIS1 and CENTERAXIS2 are used to center the subarray readout on the target spectrum, which will be displaced from the direct image of the target, in agreement with programs 16039, 16695, and 17082. We match the subarray size of the science exposures. We use FLASH=20 to meet the nominal count level. 18140( 3) - 15-Dec-2025 13:48:25 - [ 41] Exposures ------------------------------------------------------------------------------------------------------------------------------------ Exp | Target | Instr | Oper. | Aper |Spectral|Central| Optional |Num| Time | Special Num | Name | Config | Mode | or FOV |Element |Waveln.| Parameters |Exp| (Total) | Requirements ------------------------------------------------------------------------------------------------------------------------------------ ------------------------------------------------------------------------------------------------------------------------------------ 2 NAME-PROXIM WFC3/UVI ACCUM UVIS G280 FLASH=16, SIZEAXIS1=2000, 27 38 S (1026 POS TARG null, -50 A-CENTAURI S SIZEAXIS2=300, S) CENTERAXIS1=2136, CENTERAXIS2=1216 Comments: With exposure time of 40 second, we remain below 50% saturation (w/ saturation at 103 seconds) (with a maximum SNR of about 500 at about 7500 Angstrom), while remaining short enough for decent time-resolution of the flaring event. We also add a FLASH of 16, which when combined with the natural background of about 4 e- per exposure will result in >20 e- and better CTE. Nominal "UVIS" aperture is ~10" above the chip gap on chip 1; a Y-postarg of about -50" places the target near the center of subarray on chip 2. SIZEAXIS1=2000 and SIZEAXIS2=300 are used to minimize data volume, while CENTERAXIS1 and CENTERAXIS2 are used to center the subarray readout on the zeroth order of G280 spectrum. These parameters are based upon similar observations obtained successfully in GOs 13574 and 15288 but have been adjusted to better center the zeroth order spectrum on the sub-array (as done successfully for 16039). ------------------------------------------------------------------------------------------------------------------------------------ 3 BIAS WFC3/UVI ACCUM UVIS DEF SIZEAXIS1=2000, SIZEAXIS2=300, 4 0.0 S (0 S CENTERAXIS1=2136, S) CENTERAXIS2=1216 ------------------------------------------------------------------------------------------------------------------------------------ Sub Exposures ------------------------------------------------------------------------------------------------------------------------------------ Target | Exp |Instr | Oper. | Aper |Spectral|Cent.|Primary |Secondary |Iteration |CR-SPLIT |Orbit |Duration Name | Num |Config | Mode | or FOV |Element |Wave.|Pattern Pos |Pattern Pos |Num |Num |Number | ------------------------------------------------------------------------------------------------------------------------------------ NAME-PROXIMA-CENTAU 1 WFC3/UVI ACCUM G280-REF F300X none none none none 1 N/A RI S NAME-PROXIMA-CENTAU 2 WFC3/UVI ACCUM UVIS G280 none none 1 none 1 N/A RI S 18140( 3) - 15-Dec-2025 13:48:25 - [ 42] Sub Exposures ------------------------------------------------------------------------------------------------------------------------------------ Target | Exp |Instr | Oper. | Aper |Spectral|Cent.|Primary |Secondary |Iteration |CR-SPLIT |Orbit |Duration Name | Num |Config | Mode | or FOV |Element |Wave.|Pattern Pos |Pattern Pos |Num |Num |Number | ------------------------------------------------------------------------------------------------------------------------------------ NAME-PROXIMA-CENTAU 2 WFC3/UVI ACCUM UVIS G280 none none 2 none 1 N/A RI S NAME-PROXIMA-CENTAU 2 WFC3/UVI ACCUM UVIS G280 none none 3 none 1 N/A RI S NAME-PROXIMA-CENTAU 2 WFC3/UVI ACCUM UVIS G280 none none 4 none 1 N/A RI S NAME-PROXIMA-CENTAU 2 WFC3/UVI ACCUM UVIS G280 none none 5 none 1 N/A RI S NAME-PROXIMA-CENTAU 2 WFC3/UVI ACCUM UVIS G280 none none 6 none 1 N/A RI S NAME-PROXIMA-CENTAU 2 WFC3/UVI ACCUM UVIS G280 none none 7 none 1 N/A RI S NAME-PROXIMA-CENTAU 2 WFC3/UVI ACCUM UVIS G280 none none 8 none 1 N/A RI S NAME-PROXIMA-CENTAU 2 WFC3/UVI ACCUM UVIS G280 none none 9 none 1 N/A RI S NAME-PROXIMA-CENTAU 2 WFC3/UVI ACCUM UVIS G280 none none 10 none 1 N/A RI S NAME-PROXIMA-CENTAU 2 WFC3/UVI ACCUM UVIS G280 none none 11 none 1 N/A RI S NAME-PROXIMA-CENTAU 2 WFC3/UVI ACCUM UVIS G280 none none 12 none 1 N/A RI S NAME-PROXIMA-CENTAU 2 WFC3/UVI ACCUM UVIS G280 none none 13 none 1 N/A RI S NAME-PROXIMA-CENTAU 2 WFC3/UVI ACCUM UVIS G280 none none 14 none 1 N/A RI S NAME-PROXIMA-CENTAU 2 WFC3/UVI ACCUM UVIS G280 none none 15 none 1 N/A RI S NAME-PROXIMA-CENTAU 2 WFC3/UVI ACCUM UVIS G280 none none 16 none 1 N/A RI S NAME-PROXIMA-CENTAU 2 WFC3/UVI ACCUM UVIS G280 none none 17 none 1 N/A RI S NAME-PROXIMA-CENTAU 2 WFC3/UVI ACCUM UVIS G280 none none 18 none 1 N/A RI S NAME-PROXIMA-CENTAU 2 WFC3/UVI ACCUM UVIS G280 none none 19 none 1 N/A RI S NAME-PROXIMA-CENTAU 2 WFC3/UVI ACCUM UVIS G280 none none 20 none 1 N/A RI S NAME-PROXIMA-CENTAU 2 WFC3/UVI ACCUM UVIS G280 none none 21 none 1 N/A RI S NAME-PROXIMA-CENTAU 2 WFC3/UVI ACCUM UVIS G280 none none 22 none 1 N/A RI S NAME-PROXIMA-CENTAU 2 WFC3/UVI ACCUM UVIS G280 none none 23 none 1 N/A RI S NAME-PROXIMA-CENTAU 2 WFC3/UVI ACCUM UVIS G280 none none 24 none 1 N/A RI S NAME-PROXIMA-CENTAU 2 WFC3/UVI ACCUM UVIS G280 none none 25 none 1 N/A RI S 18140( 3) - 15-Dec-2025 13:48:25 - [ 43] Sub Exposures ------------------------------------------------------------------------------------------------------------------------------------ Target | Exp |Instr | Oper. | Aper |Spectral|Cent.|Primary |Secondary |Iteration |CR-SPLIT |Orbit |Duration Name | Num |Config | Mode | or FOV |Element |Wave.|Pattern Pos |Pattern Pos |Num |Num |Number | ------------------------------------------------------------------------------------------------------------------------------------ NAME-PROXIMA-CENTAU 2 WFC3/UVI ACCUM UVIS G280 none none 26 none 1 N/A RI S NAME-PROXIMA-CENTAU 2 WFC3/UVI ACCUM UVIS G280 none none 27 none 1 N/A RI S BIAS 3 WFC3/UVI ACCUM UVIS DEF none none 1 none 1 N/A S BIAS 3 WFC3/UVI ACCUM UVIS DEF none none 2 none 1 N/A S BIAS 3 WFC3/UVI ACCUM UVIS DEF none none 3 none 1 N/A S BIAS 3 WFC3/UVI ACCUM UVIS DEF none none 4 none 1 N/A S 18140( 3) - 15-Dec-2025 13:48:25 - [ 44] Visit: 11 Visit Requirements: ORIENT 0D TO 20 D; ORIENT 50D TO 120 D; ORIENT 180D TO 200 D; ORIENT 230D TO 300 D On Hold Comments: Additional Comments: The optional parameters SIZEAXIS1=2000 and SIZEAXIS2=300 are used for all exposures to minimize the data volume and hence time lost to buffer dumps. This is fine for the data that needs to be obtained because the spectum will occupy only a narrow swath of pixel rows within the field. This also requires the use of optional parameters CENTERAXIS1 and CENTERAXIS2 in order to "steer" the location of the subarray readout so that it is centered on the target spectrum. If we were positioning on chip 1 we could set CENTERAXIS2=TARGET. However, for the field center (nominal "UVIS" aperture) location on chip 2, we cannot center the subarray on the target because this would cause the subarray to extend into the chip gap, so we hardwire CENTERAXIS1=2136 and CENTERAXIS2=1216, which is intended to put the vertical center of the subarray on the zeroth order of the target spectrum. Chip 2 biases are taken at the end of the visit because the grism exposures use custom subarrays, which will not have matching biases from the WFC3 bias calibration program. For each visit we have phase constraints around the event of the planetary transit, both the orbital period of the planet and the phasing needed are placed on the target acq exposure. To avoid any contamination by several dim, nearby stars, we have placed Orient Ranges for the observations to reach our science goals. This results in ~15 transit opportunities for the UVIS observations in the coming months. Exposures ------------------------------------------------------------------------------------------------------------------------------------ Exp | Target | Instr | Oper. | Aper |Spectral|Central| Optional |Num| Time | Special Num | Name | Config | Mode | or FOV |Element |Waveln.| Parameters |Exp| (Total) | Requirements ------------------------------------------------------------------------------------------------------------------------------------ 1 NAME-PROXIM WFC3/UVI ACCUM G280-REF F300X FLASH=20, CENTERAXIS1=2136, 1 19 S (19 POS TARG null, -50; SEQ A-CENTAURI S CENTERAXIS2=1216, S) 1-3 NON-INT SIZEAXIS1=2000, SIZEAXIS2=300 Comments: For the reference image ("filter acq"), saturation in 259 seconds. 19.3 seconds gives SNR of 150. The nominal "UVIS" aperture is ~10" above the chip gap on chip 1; a Y-postarg of about -50" places the target near the center of subarray on chip 2, at an approximate XY position of (2048, 1024). CENTERAXIS1 and CENTERAXIS2 are used to center the subarray readout on the target spectrum, which will be displaced from the direct image of the target, in agreement with programs 16039, 16695, and 17082. We match the subarray size of the science exposures. We use FLASH=20 to meet the nominal count level. 18140( 3) - 15-Dec-2025 13:48:25 - [ 45] Exposures ------------------------------------------------------------------------------------------------------------------------------------ Exp | Target | Instr | Oper. | Aper |Spectral|Central| Optional |Num| Time | Special Num | Name | Config | Mode | or FOV |Element |Waveln.| Parameters |Exp| (Total) | Requirements ------------------------------------------------------------------------------------------------------------------------------------ ------------------------------------------------------------------------------------------------------------------------------------ 2 NAME-PROXIM WFC3/UVI ACCUM UVIS G280 FLASH=16, SIZEAXIS1=2000, 27 38 S (1026 POS TARG null, -50 A-CENTAURI S SIZEAXIS2=300, S) CENTERAXIS1=2136, CENTERAXIS2=1216 Comments: With exposure time of 40 second, we remain below 50% saturation (w/ saturation at 103 seconds) (with a maximum SNR of about 500 at about 7500 Angstrom), while remaining short enough for decent time-resolution of the flaring event. We also add a FLASH of 16, which when combined with the natural background of about 4 e- per exposure will result in >20 e- and better CTE. Nominal "UVIS" aperture is ~10" above the chip gap on chip 1; a Y-postarg of about -50" places the target near the center of subarray on chip 2. SIZEAXIS1=2000 and SIZEAXIS2=300 are used to minimize data volume, while CENTERAXIS1 and CENTERAXIS2 are used to center the subarray readout on the zeroth order of G280 spectrum. These parameters are based upon similar observations obtained successfully in GOs 13574 and 15288 but have been adjusted to better center the zeroth order spectrum on the sub-array (as done successfully for 16039). ------------------------------------------------------------------------------------------------------------------------------------ 3 BIAS WFC3/UVI ACCUM UVIS DEF SIZEAXIS1=2000, SIZEAXIS2=300, 4 0.0 S (0 S CENTERAXIS1=2136, S) CENTERAXIS2=1216 ------------------------------------------------------------------------------------------------------------------------------------ Sub Exposures ------------------------------------------------------------------------------------------------------------------------------------ Target | Exp |Instr | Oper. | Aper |Spectral|Cent.|Primary |Secondary |Iteration |CR-SPLIT |Orbit |Duration Name | Num |Config | Mode | or FOV |Element |Wave.|Pattern Pos |Pattern Pos |Num |Num |Number | ------------------------------------------------------------------------------------------------------------------------------------ NAME-PROXIMA-CENTAU 1 WFC3/UVI ACCUM G280-REF F300X none none none none 1 N/A RI S NAME-PROXIMA-CENTAU 2 WFC3/UVI ACCUM UVIS G280 none none 1 none 1 N/A RI S 18140( 3) - 15-Dec-2025 13:48:25 - [ 46] Sub Exposures ------------------------------------------------------------------------------------------------------------------------------------ Target | Exp |Instr | Oper. | Aper |Spectral|Cent.|Primary |Secondary |Iteration |CR-SPLIT |Orbit |Duration Name | Num |Config | Mode | or FOV |Element |Wave.|Pattern Pos |Pattern Pos |Num |Num |Number | ------------------------------------------------------------------------------------------------------------------------------------ NAME-PROXIMA-CENTAU 2 WFC3/UVI ACCUM UVIS G280 none none 2 none 1 N/A RI S NAME-PROXIMA-CENTAU 2 WFC3/UVI ACCUM UVIS G280 none none 3 none 1 N/A RI S NAME-PROXIMA-CENTAU 2 WFC3/UVI ACCUM UVIS G280 none none 4 none 1 N/A RI S NAME-PROXIMA-CENTAU 2 WFC3/UVI ACCUM UVIS G280 none none 5 none 1 N/A RI S NAME-PROXIMA-CENTAU 2 WFC3/UVI ACCUM UVIS G280 none none 6 none 1 N/A RI S NAME-PROXIMA-CENTAU 2 WFC3/UVI ACCUM UVIS G280 none none 7 none 1 N/A RI S NAME-PROXIMA-CENTAU 2 WFC3/UVI ACCUM UVIS G280 none none 8 none 1 N/A RI S NAME-PROXIMA-CENTAU 2 WFC3/UVI ACCUM UVIS G280 none none 9 none 1 N/A RI S NAME-PROXIMA-CENTAU 2 WFC3/UVI ACCUM UVIS G280 none none 10 none 1 N/A RI S NAME-PROXIMA-CENTAU 2 WFC3/UVI ACCUM UVIS G280 none none 11 none 1 N/A RI S NAME-PROXIMA-CENTAU 2 WFC3/UVI ACCUM UVIS G280 none none 12 none 1 N/A RI S NAME-PROXIMA-CENTAU 2 WFC3/UVI ACCUM UVIS G280 none none 13 none 1 N/A RI S NAME-PROXIMA-CENTAU 2 WFC3/UVI ACCUM UVIS G280 none none 14 none 1 N/A RI S NAME-PROXIMA-CENTAU 2 WFC3/UVI ACCUM UVIS G280 none none 15 none 1 N/A RI S NAME-PROXIMA-CENTAU 2 WFC3/UVI ACCUM UVIS G280 none none 16 none 1 N/A RI S NAME-PROXIMA-CENTAU 2 WFC3/UVI ACCUM UVIS G280 none none 17 none 1 N/A RI S NAME-PROXIMA-CENTAU 2 WFC3/UVI ACCUM UVIS G280 none none 18 none 1 N/A RI S NAME-PROXIMA-CENTAU 2 WFC3/UVI ACCUM UVIS G280 none none 19 none 1 N/A RI S NAME-PROXIMA-CENTAU 2 WFC3/UVI ACCUM UVIS G280 none none 20 none 1 N/A RI S NAME-PROXIMA-CENTAU 2 WFC3/UVI ACCUM UVIS G280 none none 21 none 1 N/A RI S NAME-PROXIMA-CENTAU 2 WFC3/UVI ACCUM UVIS G280 none none 22 none 1 N/A RI S NAME-PROXIMA-CENTAU 2 WFC3/UVI ACCUM UVIS G280 none none 23 none 1 N/A RI S NAME-PROXIMA-CENTAU 2 WFC3/UVI ACCUM UVIS G280 none none 24 none 1 N/A RI S NAME-PROXIMA-CENTAU 2 WFC3/UVI ACCUM UVIS G280 none none 25 none 1 N/A RI S 18140( 3) - 15-Dec-2025 13:48:25 - [ 47] Sub Exposures ------------------------------------------------------------------------------------------------------------------------------------ Target | Exp |Instr | Oper. | Aper |Spectral|Cent.|Primary |Secondary |Iteration |CR-SPLIT |Orbit |Duration Name | Num |Config | Mode | or FOV |Element |Wave.|Pattern Pos |Pattern Pos |Num |Num |Number | ------------------------------------------------------------------------------------------------------------------------------------ NAME-PROXIMA-CENTAU 2 WFC3/UVI ACCUM UVIS G280 none none 26 none 1 N/A RI S NAME-PROXIMA-CENTAU 2 WFC3/UVI ACCUM UVIS G280 none none 27 none 1 N/A RI S BIAS 3 WFC3/UVI ACCUM UVIS DEF none none 1 none 1 N/A S BIAS 3 WFC3/UVI ACCUM UVIS DEF none none 2 none 1 N/A S BIAS 3 WFC3/UVI ACCUM UVIS DEF none none 3 none 1 N/A S BIAS 3 WFC3/UVI ACCUM UVIS DEF none none 4 none 1 N/A S 18140( 3) - 15-Dec-2025 13:48:25 - [ 48] Visit: 12 Visit Requirements: ORIENT 0D TO 20 D; ORIENT 50D TO 120 D; ORIENT 180D TO 200 D; ORIENT 230D TO 300 D On Hold Comments: Additional Comments: The optional parameters SIZEAXIS1=2000 and SIZEAXIS2=300 are used for all exposures to minimize the data volume and hence time lost to buffer dumps. This is fine for the data that needs to be obtained because the spectum will occupy only a narrow swath of pixel rows within the field. This also requires the use of optional parameters CENTERAXIS1 and CENTERAXIS2 in order to "steer" the location of the subarray readout so that it is centered on the target spectrum. If we were positioning on chip 1 we could set CENTERAXIS2=TARGET. However, for the field center (nominal "UVIS" aperture) location on chip 2, we cannot center the subarray on the target because this would cause the subarray to extend into the chip gap, so we hardwire CENTERAXIS1=2136 and CENTERAXIS2=1216, which is intended to put the vertical center of the subarray on the zeroth order of the target spectrum. Chip 2 biases are taken at the end of the visit because the grism exposures use custom subarrays, which will not have matching biases from the WFC3 bias calibration program. For each visit we have phase constraints around the event of the planetary transit, both the orbital period of the planet and the phasing needed are placed on the target acq exposure. To avoid any contamination by several dim, nearby stars, we have placed Orient Ranges for the observations to reach our science goals. This results in ~15 transit opportunities for the UVIS observations in the coming months. Exposures ------------------------------------------------------------------------------------------------------------------------------------ Exp | Target | Instr | Oper. | Aper |Spectral|Central| Optional |Num| Time | Special Num | Name | Config | Mode | or FOV |Element |Waveln.| Parameters |Exp| (Total) | Requirements ------------------------------------------------------------------------------------------------------------------------------------ 1 NAME-PROXIM WFC3/UVI ACCUM G280-REF F300X FLASH=20, CENTERAXIS1=2136, 1 19 S (19 POS TARG null, -50; SEQ A-CENTAURI S CENTERAXIS2=1216, S) 1-3 NON-INT SIZEAXIS1=2000, SIZEAXIS2=300 Comments: For the reference image ("filter acq"), saturation in 259 seconds. 19.3 seconds gives SNR of 150. The nominal "UVIS" aperture is ~10" above the chip gap on chip 1; a Y-postarg of about -50" places the target near the center of subarray on chip 2, at an approximate XY position of (2048, 1024). CENTERAXIS1 and CENTERAXIS2 are used to center the subarray readout on the target spectrum, which will be displaced from the direct image of the target, in agreement with programs 16039, 16695, and 17082. We match the subarray size of the science exposures. We use FLASH=20 to meet the nominal count level. 18140( 3) - 15-Dec-2025 13:48:25 - [ 49] Exposures ------------------------------------------------------------------------------------------------------------------------------------ Exp | Target | Instr | Oper. | Aper |Spectral|Central| Optional |Num| Time | Special Num | Name | Config | Mode | or FOV |Element |Waveln.| Parameters |Exp| (Total) | Requirements ------------------------------------------------------------------------------------------------------------------------------------ ------------------------------------------------------------------------------------------------------------------------------------ 2 NAME-PROXIM WFC3/UVI ACCUM UVIS G280 FLASH=16, SIZEAXIS1=2000, 27 38 S (1026 POS TARG null, -50 A-CENTAURI S SIZEAXIS2=300, S) CENTERAXIS1=2136, CENTERAXIS2=1216 Comments: With exposure time of 40 second, we remain below 50% saturation (w/ saturation at 103 seconds) (with a maximum SNR of about 500 at about 7500 Angstrom), while remaining short enough for decent time-resolution of the flaring event. We also add a FLASH of 16, which when combined with the natural background of about 4 e- per exposure will result in >20 e- and better CTE. Nominal "UVIS" aperture is ~10" above the chip gap on chip 1; a Y-postarg of about -50" places the target near the center of subarray on chip 2. SIZEAXIS1=2000 and SIZEAXIS2=300 are used to minimize data volume, while CENTERAXIS1 and CENTERAXIS2 are used to center the subarray readout on the zeroth order of G280 spectrum. These parameters are based upon similar observations obtained successfully in GOs 13574 and 15288 but have been adjusted to better center the zeroth order spectrum on the sub-array (as done successfully for 16039). ------------------------------------------------------------------------------------------------------------------------------------ 3 BIAS WFC3/UVI ACCUM UVIS DEF SIZEAXIS1=2000, SIZEAXIS2=300, 4 0.0 S (0 S CENTERAXIS1=2136, S) CENTERAXIS2=1216 ------------------------------------------------------------------------------------------------------------------------------------ Sub Exposures ------------------------------------------------------------------------------------------------------------------------------------ Target | Exp |Instr | Oper. | Aper |Spectral|Cent.|Primary |Secondary |Iteration |CR-SPLIT |Orbit |Duration Name | Num |Config | Mode | or FOV |Element |Wave.|Pattern Pos |Pattern Pos |Num |Num |Number | ------------------------------------------------------------------------------------------------------------------------------------ NAME-PROXIMA-CENTAU 1 WFC3/UVI ACCUM G280-REF F300X none none none none 1 N/A RI S NAME-PROXIMA-CENTAU 2 WFC3/UVI ACCUM UVIS G280 none none 1 none 1 N/A RI S 18140( 3) - 15-Dec-2025 13:48:25 - [ 50] Sub Exposures ------------------------------------------------------------------------------------------------------------------------------------ Target | Exp |Instr | Oper. | Aper |Spectral|Cent.|Primary |Secondary |Iteration |CR-SPLIT |Orbit |Duration Name | Num |Config | Mode | or FOV |Element |Wave.|Pattern Pos |Pattern Pos |Num |Num |Number | ------------------------------------------------------------------------------------------------------------------------------------ NAME-PROXIMA-CENTAU 2 WFC3/UVI ACCUM UVIS G280 none none 2 none 1 N/A RI S NAME-PROXIMA-CENTAU 2 WFC3/UVI ACCUM UVIS G280 none none 3 none 1 N/A RI S NAME-PROXIMA-CENTAU 2 WFC3/UVI ACCUM UVIS G280 none none 4 none 1 N/A RI S NAME-PROXIMA-CENTAU 2 WFC3/UVI ACCUM UVIS G280 none none 5 none 1 N/A RI S NAME-PROXIMA-CENTAU 2 WFC3/UVI ACCUM UVIS G280 none none 6 none 1 N/A RI S NAME-PROXIMA-CENTAU 2 WFC3/UVI ACCUM UVIS G280 none none 7 none 1 N/A RI S NAME-PROXIMA-CENTAU 2 WFC3/UVI ACCUM UVIS G280 none none 8 none 1 N/A RI S NAME-PROXIMA-CENTAU 2 WFC3/UVI ACCUM UVIS G280 none none 9 none 1 N/A RI S NAME-PROXIMA-CENTAU 2 WFC3/UVI ACCUM UVIS G280 none none 10 none 1 N/A RI S NAME-PROXIMA-CENTAU 2 WFC3/UVI ACCUM UVIS G280 none none 11 none 1 N/A RI S NAME-PROXIMA-CENTAU 2 WFC3/UVI ACCUM UVIS G280 none none 12 none 1 N/A RI S NAME-PROXIMA-CENTAU 2 WFC3/UVI ACCUM UVIS G280 none none 13 none 1 N/A RI S NAME-PROXIMA-CENTAU 2 WFC3/UVI ACCUM UVIS G280 none none 14 none 1 N/A RI S NAME-PROXIMA-CENTAU 2 WFC3/UVI ACCUM UVIS G280 none none 15 none 1 N/A RI S NAME-PROXIMA-CENTAU 2 WFC3/UVI ACCUM UVIS G280 none none 16 none 1 N/A RI S NAME-PROXIMA-CENTAU 2 WFC3/UVI ACCUM UVIS G280 none none 17 none 1 N/A RI S NAME-PROXIMA-CENTAU 2 WFC3/UVI ACCUM UVIS G280 none none 18 none 1 N/A RI S NAME-PROXIMA-CENTAU 2 WFC3/UVI ACCUM UVIS G280 none none 19 none 1 N/A RI S NAME-PROXIMA-CENTAU 2 WFC3/UVI ACCUM UVIS G280 none none 20 none 1 N/A RI S NAME-PROXIMA-CENTAU 2 WFC3/UVI ACCUM UVIS G280 none none 21 none 1 N/A RI S NAME-PROXIMA-CENTAU 2 WFC3/UVI ACCUM UVIS G280 none none 22 none 1 N/A RI S NAME-PROXIMA-CENTAU 2 WFC3/UVI ACCUM UVIS G280 none none 23 none 1 N/A RI S NAME-PROXIMA-CENTAU 2 WFC3/UVI ACCUM UVIS G280 none none 24 none 1 N/A RI S NAME-PROXIMA-CENTAU 2 WFC3/UVI ACCUM UVIS G280 none none 25 none 1 N/A RI S 18140( 3) - 15-Dec-2025 13:48:25 - [ 51] Sub Exposures ------------------------------------------------------------------------------------------------------------------------------------ Target | Exp |Instr | Oper. | Aper |Spectral|Cent.|Primary |Secondary |Iteration |CR-SPLIT |Orbit |Duration Name | Num |Config | Mode | or FOV |Element |Wave.|Pattern Pos |Pattern Pos |Num |Num |Number | ------------------------------------------------------------------------------------------------------------------------------------ NAME-PROXIMA-CENTAU 2 WFC3/UVI ACCUM UVIS G280 none none 26 none 1 N/A RI S NAME-PROXIMA-CENTAU 2 WFC3/UVI ACCUM UVIS G280 none none 27 none 1 N/A RI S BIAS 3 WFC3/UVI ACCUM UVIS DEF none none 1 none 1 N/A S BIAS 3 WFC3/UVI ACCUM UVIS DEF none none 2 none 1 N/A S BIAS 3 WFC3/UVI ACCUM UVIS DEF none none 3 none 1 N/A S BIAS 3 WFC3/UVI ACCUM UVIS DEF none none 4 none 1 N/A S 18140( 3) - 15-Dec-2025 13:48:25 - [ 52] Visit: 13 Visit Requirements: ORIENT 0D TO 20 D; ORIENT 50D TO 120 D; ORIENT 180D TO 200 D; ORIENT 230D TO 300 D On Hold Comments: Additional Comments: The optional parameters SIZEAXIS1=2000 and SIZEAXIS2=300 are used for all exposures to minimize the data volume and hence time lost to buffer dumps. This is fine for the data that needs to be obtained because the spectum will occupy only a narrow swath of pixel rows within the field. This also requires the use of optional parameters CENTERAXIS1 and CENTERAXIS2 in order to "steer" the location of the subarray readout so that it is centered on the target spectrum. If we were positioning on chip 1 we could set CENTERAXIS2=TARGET. However, for the field center (nominal "UVIS" aperture) location on chip 2, we cannot center the subarray on the target because this would cause the subarray to extend into the chip gap, so we hardwire CENTERAXIS1=2136 and CENTERAXIS2=1216, which is intended to put the vertical center of the subarray on the zeroth order of the target spectrum. Chip 2 biases are taken at the end of the visit because the grism exposures use custom subarrays, which will not have matching biases from the WFC3 bias calibration program. For each visit we have phase constraints around the event of the planetary transit, both the orbital period of the planet and the phasing needed are placed on the target acq exposure. To avoid any contamination by several dim, nearby stars, we have placed Orient Ranges for the observations to reach our science goals. This results in ~15 transit opportunities for the UVIS observations in the coming months. Exposures ------------------------------------------------------------------------------------------------------------------------------------ Exp | Target | Instr | Oper. | Aper |Spectral|Central| Optional |Num| Time | Special Num | Name | Config | Mode | or FOV |Element |Waveln.| Parameters |Exp| (Total) | Requirements ------------------------------------------------------------------------------------------------------------------------------------ 1 NAME-PROXIM WFC3/UVI ACCUM G280-REF F300X FLASH=20, CENTERAXIS1=2136, 1 19 S (19 POS TARG null, -50; SEQ A-CENTAURI S CENTERAXIS2=1216, S) 1-3 NON-INT SIZEAXIS1=2000, SIZEAXIS2=300 Comments: For the reference image ("filter acq"), saturation in 259 seconds. 19.3 seconds gives SNR of 150. The nominal "UVIS" aperture is ~10" above the chip gap on chip 1; a Y-postarg of about -50" places the target near the center of subarray on chip 2, at an approximate XY position of (2048, 1024). CENTERAXIS1 and CENTERAXIS2 are used to center the subarray readout on the target spectrum, which will be displaced from the direct image of the target, in agreement with programs 16039, 16695, and 17082. We match the subarray size of the science exposures. We use FLASH=20 to meet the nominal count level. 18140( 3) - 15-Dec-2025 13:48:25 - [ 53] Exposures ------------------------------------------------------------------------------------------------------------------------------------ Exp | Target | Instr | Oper. | Aper |Spectral|Central| Optional |Num| Time | Special Num | Name | Config | Mode | or FOV |Element |Waveln.| Parameters |Exp| (Total) | Requirements ------------------------------------------------------------------------------------------------------------------------------------ ------------------------------------------------------------------------------------------------------------------------------------ 2 NAME-PROXIM WFC3/UVI ACCUM UVIS G280 FLASH=16, SIZEAXIS1=2000, 27 38 S (1026 POS TARG null, -50 A-CENTAURI S SIZEAXIS2=300, S) CENTERAXIS1=2136, CENTERAXIS2=1216 Comments: With exposure time of 40 second, we remain below 50% saturation (w/ saturation at 103 seconds) (with a maximum SNR of about 500 at about 7500 Angstrom), while remaining short enough for decent time-resolution of the flaring event. We also add a FLASH of 16, which when combined with the natural background of about 4 e- per exposure will result in >20 e- and better CTE. Nominal "UVIS" aperture is ~10" above the chip gap on chip 1; a Y-postarg of about -50" places the target near the center of subarray on chip 2. SIZEAXIS1=2000 and SIZEAXIS2=300 are used to minimize data volume, while CENTERAXIS1 and CENTERAXIS2 are used to center the subarray readout on the zeroth order of G280 spectrum. These parameters are based upon similar observations obtained successfully in GOs 13574 and 15288 but have been adjusted to better center the zeroth order spectrum on the sub-array (as done successfully for 16039). ------------------------------------------------------------------------------------------------------------------------------------ 3 BIAS WFC3/UVI ACCUM UVIS DEF SIZEAXIS1=2000, SIZEAXIS2=300, 4 0.0 S (0 S CENTERAXIS1=2136, S) CENTERAXIS2=1216 ------------------------------------------------------------------------------------------------------------------------------------ Sub Exposures ------------------------------------------------------------------------------------------------------------------------------------ Target | Exp |Instr | Oper. | Aper |Spectral|Cent.|Primary |Secondary |Iteration |CR-SPLIT |Orbit |Duration Name | Num |Config | Mode | or FOV |Element |Wave.|Pattern Pos |Pattern Pos |Num |Num |Number | ------------------------------------------------------------------------------------------------------------------------------------ NAME-PROXIMA-CENTAU 1 WFC3/UVI ACCUM G280-REF F300X none none none none 1 N/A RI S NAME-PROXIMA-CENTAU 2 WFC3/UVI ACCUM UVIS G280 none none 1 none 1 N/A RI S 18140( 3) - 15-Dec-2025 13:48:25 - [ 54] Sub Exposures ------------------------------------------------------------------------------------------------------------------------------------ Target | Exp |Instr | Oper. | Aper |Spectral|Cent.|Primary |Secondary |Iteration |CR-SPLIT |Orbit |Duration Name | Num |Config | Mode | or FOV |Element |Wave.|Pattern Pos |Pattern Pos |Num |Num |Number | ------------------------------------------------------------------------------------------------------------------------------------ NAME-PROXIMA-CENTAU 2 WFC3/UVI ACCUM UVIS G280 none none 2 none 1 N/A RI S NAME-PROXIMA-CENTAU 2 WFC3/UVI ACCUM UVIS G280 none none 3 none 1 N/A RI S NAME-PROXIMA-CENTAU 2 WFC3/UVI ACCUM UVIS G280 none none 4 none 1 N/A RI S NAME-PROXIMA-CENTAU 2 WFC3/UVI ACCUM UVIS G280 none none 5 none 1 N/A RI S NAME-PROXIMA-CENTAU 2 WFC3/UVI ACCUM UVIS G280 none none 6 none 1 N/A RI S NAME-PROXIMA-CENTAU 2 WFC3/UVI ACCUM UVIS G280 none none 7 none 1 N/A RI S NAME-PROXIMA-CENTAU 2 WFC3/UVI ACCUM UVIS G280 none none 8 none 1 N/A RI S NAME-PROXIMA-CENTAU 2 WFC3/UVI ACCUM UVIS G280 none none 9 none 1 N/A RI S NAME-PROXIMA-CENTAU 2 WFC3/UVI ACCUM UVIS G280 none none 10 none 1 N/A RI S NAME-PROXIMA-CENTAU 2 WFC3/UVI ACCUM UVIS G280 none none 11 none 1 N/A RI S NAME-PROXIMA-CENTAU 2 WFC3/UVI ACCUM UVIS G280 none none 12 none 1 N/A RI S NAME-PROXIMA-CENTAU 2 WFC3/UVI ACCUM UVIS G280 none none 13 none 1 N/A RI S NAME-PROXIMA-CENTAU 2 WFC3/UVI ACCUM UVIS G280 none none 14 none 1 N/A RI S NAME-PROXIMA-CENTAU 2 WFC3/UVI ACCUM UVIS G280 none none 15 none 1 N/A RI S NAME-PROXIMA-CENTAU 2 WFC3/UVI ACCUM UVIS G280 none none 16 none 1 N/A RI S NAME-PROXIMA-CENTAU 2 WFC3/UVI ACCUM UVIS G280 none none 17 none 1 N/A RI S NAME-PROXIMA-CENTAU 2 WFC3/UVI ACCUM UVIS G280 none none 18 none 1 N/A RI S NAME-PROXIMA-CENTAU 2 WFC3/UVI ACCUM UVIS G280 none none 19 none 1 N/A RI S NAME-PROXIMA-CENTAU 2 WFC3/UVI ACCUM UVIS G280 none none 20 none 1 N/A RI S NAME-PROXIMA-CENTAU 2 WFC3/UVI ACCUM UVIS G280 none none 21 none 1 N/A RI S NAME-PROXIMA-CENTAU 2 WFC3/UVI ACCUM UVIS G280 none none 22 none 1 N/A RI S NAME-PROXIMA-CENTAU 2 WFC3/UVI ACCUM UVIS G280 none none 23 none 1 N/A RI S NAME-PROXIMA-CENTAU 2 WFC3/UVI ACCUM UVIS G280 none none 24 none 1 N/A RI S NAME-PROXIMA-CENTAU 2 WFC3/UVI ACCUM UVIS G280 none none 25 none 1 N/A RI S 18140( 3) - 15-Dec-2025 13:48:25 - [ 55] Sub Exposures ------------------------------------------------------------------------------------------------------------------------------------ Target | Exp |Instr | Oper. | Aper |Spectral|Cent.|Primary |Secondary |Iteration |CR-SPLIT |Orbit |Duration Name | Num |Config | Mode | or FOV |Element |Wave.|Pattern Pos |Pattern Pos |Num |Num |Number | ------------------------------------------------------------------------------------------------------------------------------------ NAME-PROXIMA-CENTAU 2 WFC3/UVI ACCUM UVIS G280 none none 26 none 1 N/A RI S NAME-PROXIMA-CENTAU 2 WFC3/UVI ACCUM UVIS G280 none none 27 none 1 N/A RI S BIAS 3 WFC3/UVI ACCUM UVIS DEF none none 1 none 1 N/A S BIAS 3 WFC3/UVI ACCUM UVIS DEF none none 2 none 1 N/A S BIAS 3 WFC3/UVI ACCUM UVIS DEF none none 3 none 1 N/A S BIAS 3 WFC3/UVI ACCUM UVIS DEF none none 4 none 1 N/A S 18140( 3) - 15-Dec-2025 13:48:25 - [ 56] Visit: 14 Visit Requirements: ORIENT 0D TO 20 D; ORIENT 50D TO 120 D; ORIENT 180D TO 200 D; ORIENT 230D TO 300 D On Hold Comments: Additional Comments: The optional parameters SIZEAXIS1=2000 and SIZEAXIS2=300 are used for all exposures to minimize the data volume and hence time lost to buffer dumps. This is fine for the data that needs to be obtained because the spectum will occupy only a narrow swath of pixel rows within the field. This also requires the use of optional parameters CENTERAXIS1 and CENTERAXIS2 in order to "steer" the location of the subarray readout so that it is centered on the target spectrum. If we were positioning on chip 1 we could set CENTERAXIS2=TARGET. However, for the field center (nominal "UVIS" aperture) location on chip 2, we cannot center the subarray on the target because this would cause the subarray to extend into the chip gap, so we hardwire CENTERAXIS1=2136 and CENTERAXIS2=1216, which is intended to put the vertical center of the subarray on the zeroth order of the target spectrum. Chip 2 biases are taken at the end of the visit because the grism exposures use custom subarrays, which will not have matching biases from the WFC3 bias calibration program. For each visit we have phase constraints around the event of the planetary transit, both the orbital period of the planet and the phasing needed are placed on the target acq exposure. To avoid any contamination by several dim, nearby stars, we have placed Orient Ranges for the observations to reach our science goals. This results in ~15 transit opportunities for the UVIS observations in the coming months. Exposures ------------------------------------------------------------------------------------------------------------------------------------ Exp | Target | Instr | Oper. | Aper |Spectral|Central| Optional |Num| Time | Special Num | Name | Config | Mode | or FOV |Element |Waveln.| Parameters |Exp| (Total) | Requirements ------------------------------------------------------------------------------------------------------------------------------------ 1 NAME-PROXIM WFC3/UVI ACCUM G280-REF F300X FLASH=20, CENTERAXIS1=2136, 1 19 S (19 POS TARG null, -50; SEQ A-CENTAURI S CENTERAXIS2=1216, S) 1-3 NON-INT SIZEAXIS1=2000, SIZEAXIS2=300 Comments: For the reference image ("filter acq"), saturation in 259 seconds. 19.3 seconds gives SNR of 150. The nominal "UVIS" aperture is ~10" above the chip gap on chip 1; a Y-postarg of about -50" places the target near the center of subarray on chip 2, at an approximate XY position of (2048, 1024). CENTERAXIS1 and CENTERAXIS2 are used to center the subarray readout on the target spectrum, which will be displaced from the direct image of the target, in agreement with programs 16039, 16695, and 17082. We match the subarray size of the science exposures. We use FLASH=20 to meet the nominal count level. 18140( 3) - 15-Dec-2025 13:48:25 - [ 57] Exposures ------------------------------------------------------------------------------------------------------------------------------------ Exp | Target | Instr | Oper. | Aper |Spectral|Central| Optional |Num| Time | Special Num | Name | Config | Mode | or FOV |Element |Waveln.| Parameters |Exp| (Total) | Requirements ------------------------------------------------------------------------------------------------------------------------------------ ------------------------------------------------------------------------------------------------------------------------------------ 2 NAME-PROXIM WFC3/UVI ACCUM UVIS G280 FLASH=16, SIZEAXIS1=2000, 27 38 S (1026 POS TARG null, -50 A-CENTAURI S SIZEAXIS2=300, S) CENTERAXIS1=2136, CENTERAXIS2=1216 Comments: With exposure time of 40 second, we remain below 50% saturation (w/ saturation at 103 seconds) (with a maximum SNR of about 500 at about 7500 Angstrom), while remaining short enough for decent time-resolution of the flaring event. We also add a FLASH of 16, which when combined with the natural background of about 4 e- per exposure will result in >20 e- and better CTE. Nominal "UVIS" aperture is ~10" above the chip gap on chip 1; a Y-postarg of about -50" places the target near the center of subarray on chip 2. SIZEAXIS1=2000 and SIZEAXIS2=300 are used to minimize data volume, while CENTERAXIS1 and CENTERAXIS2 are used to center the subarray readout on the zeroth order of G280 spectrum. These parameters are based upon similar observations obtained successfully in GOs 13574 and 15288 but have been adjusted to better center the zeroth order spectrum on the sub-array (as done successfully for 16039). ------------------------------------------------------------------------------------------------------------------------------------ 3 BIAS WFC3/UVI ACCUM UVIS DEF SIZEAXIS1=2000, SIZEAXIS2=300, 4 0.0 S (0 S CENTERAXIS1=2136, S) CENTERAXIS2=1216 ------------------------------------------------------------------------------------------------------------------------------------ Sub Exposures ------------------------------------------------------------------------------------------------------------------------------------ Target | Exp |Instr | Oper. | Aper |Spectral|Cent.|Primary |Secondary |Iteration |CR-SPLIT |Orbit |Duration Name | Num |Config | Mode | or FOV |Element |Wave.|Pattern Pos |Pattern Pos |Num |Num |Number | ------------------------------------------------------------------------------------------------------------------------------------ NAME-PROXIMA-CENTAU 1 WFC3/UVI ACCUM G280-REF F300X none none none none 1 N/A RI S NAME-PROXIMA-CENTAU 2 WFC3/UVI ACCUM UVIS G280 none none 1 none 1 N/A RI S 18140( 3) - 15-Dec-2025 13:48:25 - [ 58] Sub Exposures ------------------------------------------------------------------------------------------------------------------------------------ Target | Exp |Instr | Oper. | Aper |Spectral|Cent.|Primary |Secondary |Iteration |CR-SPLIT |Orbit |Duration Name | Num |Config | Mode | or FOV |Element |Wave.|Pattern Pos |Pattern Pos |Num |Num |Number | ------------------------------------------------------------------------------------------------------------------------------------ NAME-PROXIMA-CENTAU 2 WFC3/UVI ACCUM UVIS G280 none none 2 none 1 N/A RI S NAME-PROXIMA-CENTAU 2 WFC3/UVI ACCUM UVIS G280 none none 3 none 1 N/A RI S NAME-PROXIMA-CENTAU 2 WFC3/UVI ACCUM UVIS G280 none none 4 none 1 N/A RI S NAME-PROXIMA-CENTAU 2 WFC3/UVI ACCUM UVIS G280 none none 5 none 1 N/A RI S NAME-PROXIMA-CENTAU 2 WFC3/UVI ACCUM UVIS G280 none none 6 none 1 N/A RI S NAME-PROXIMA-CENTAU 2 WFC3/UVI ACCUM UVIS G280 none none 7 none 1 N/A RI S NAME-PROXIMA-CENTAU 2 WFC3/UVI ACCUM UVIS G280 none none 8 none 1 N/A RI S NAME-PROXIMA-CENTAU 2 WFC3/UVI ACCUM UVIS G280 none none 9 none 1 N/A RI S NAME-PROXIMA-CENTAU 2 WFC3/UVI ACCUM UVIS G280 none none 10 none 1 N/A RI S NAME-PROXIMA-CENTAU 2 WFC3/UVI ACCUM UVIS G280 none none 11 none 1 N/A RI S NAME-PROXIMA-CENTAU 2 WFC3/UVI ACCUM UVIS G280 none none 12 none 1 N/A RI S NAME-PROXIMA-CENTAU 2 WFC3/UVI ACCUM UVIS G280 none none 13 none 1 N/A RI S NAME-PROXIMA-CENTAU 2 WFC3/UVI ACCUM UVIS G280 none none 14 none 1 N/A RI S NAME-PROXIMA-CENTAU 2 WFC3/UVI ACCUM UVIS G280 none none 15 none 1 N/A RI S NAME-PROXIMA-CENTAU 2 WFC3/UVI ACCUM UVIS G280 none none 16 none 1 N/A RI S NAME-PROXIMA-CENTAU 2 WFC3/UVI ACCUM UVIS G280 none none 17 none 1 N/A RI S NAME-PROXIMA-CENTAU 2 WFC3/UVI ACCUM UVIS G280 none none 18 none 1 N/A RI S NAME-PROXIMA-CENTAU 2 WFC3/UVI ACCUM UVIS G280 none none 19 none 1 N/A RI S NAME-PROXIMA-CENTAU 2 WFC3/UVI ACCUM UVIS G280 none none 20 none 1 N/A RI S NAME-PROXIMA-CENTAU 2 WFC3/UVI ACCUM UVIS G280 none none 21 none 1 N/A RI S NAME-PROXIMA-CENTAU 2 WFC3/UVI ACCUM UVIS G280 none none 22 none 1 N/A RI S NAME-PROXIMA-CENTAU 2 WFC3/UVI ACCUM UVIS G280 none none 23 none 1 N/A RI S NAME-PROXIMA-CENTAU 2 WFC3/UVI ACCUM UVIS G280 none none 24 none 1 N/A RI S NAME-PROXIMA-CENTAU 2 WFC3/UVI ACCUM UVIS G280 none none 25 none 1 N/A RI S 18140( 3) - 15-Dec-2025 13:48:25 - [ 59] Sub Exposures ------------------------------------------------------------------------------------------------------------------------------------ Target | Exp |Instr | Oper. | Aper |Spectral|Cent.|Primary |Secondary |Iteration |CR-SPLIT |Orbit |Duration Name | Num |Config | Mode | or FOV |Element |Wave.|Pattern Pos |Pattern Pos |Num |Num |Number | ------------------------------------------------------------------------------------------------------------------------------------ NAME-PROXIMA-CENTAU 2 WFC3/UVI ACCUM UVIS G280 none none 26 none 1 N/A RI S NAME-PROXIMA-CENTAU 2 WFC3/UVI ACCUM UVIS G280 none none 27 none 1 N/A RI S BIAS 3 WFC3/UVI ACCUM UVIS DEF none none 1 none 1 N/A S BIAS 3 WFC3/UVI ACCUM UVIS DEF none none 2 none 1 N/A S BIAS 3 WFC3/UVI ACCUM UVIS DEF none none 3 none 1 N/A S BIAS 3 WFC3/UVI ACCUM UVIS DEF none none 4 none 1 N/A S 18140( 3) - 15-Dec-2025 13:48:25 - [ 60] Visit: 15 Visit Requirements: ORIENT 0D TO 20 D; ORIENT 50D TO 120 D; ORIENT 180D TO 200 D; ORIENT 230D TO 300 D On Hold Comments: Additional Comments: The optional parameters SIZEAXIS1=2000 and SIZEAXIS2=300 are used for all exposures to minimize the data volume and hence time lost to buffer dumps. This is fine for the data that needs to be obtained because the spectum will occupy only a narrow swath of pixel rows within the field. This also requires the use of optional parameters CENTERAXIS1 and CENTERAXIS2 in order to "steer" the location of the subarray readout so that it is centered on the target spectrum. If we were positioning on chip 1 we could set CENTERAXIS2=TARGET. However, for the field center (nominal "UVIS" aperture) location on chip 2, we cannot center the subarray on the target because this would cause the subarray to extend into the chip gap, so we hardwire CENTERAXIS1=2136 and CENTERAXIS2=1216, which is intended to put the vertical center of the subarray on the zeroth order of the target spectrum. Chip 2 biases are taken at the end of the visit because the grism exposures use custom subarrays, which will not have matching biases from the WFC3 bias calibration program. For each visit we have phase constraints around the event of the planetary transit, both the orbital period of the planet and the phasing needed are placed on the target acq exposure. To avoid any contamination by several dim, nearby stars, we have placed Orient Ranges for the observations to reach our science goals. This results in ~15 transit opportunities for the UVIS observations in the coming months. Exposures ------------------------------------------------------------------------------------------------------------------------------------ Exp | Target | Instr | Oper. | Aper |Spectral|Central| Optional |Num| Time | Special Num | Name | Config | Mode | or FOV |Element |Waveln.| Parameters |Exp| (Total) | Requirements ------------------------------------------------------------------------------------------------------------------------------------ 1 NAME-PROXIM WFC3/UVI ACCUM G280-REF F300X FLASH=20, CENTERAXIS1=2136, 1 19 S (19 POS TARG null, -50; SEQ A-CENTAURI S CENTERAXIS2=1216, S) 1-3 NON-INT SIZEAXIS1=2000, SIZEAXIS2=300 Comments: For the reference image ("filter acq"), saturation in 259 seconds. 19.3 seconds gives SNR of 150. The nominal "UVIS" aperture is ~10" above the chip gap on chip 1; a Y-postarg of about -50" places the target near the center of subarray on chip 2, at an approximate XY position of (2048, 1024). CENTERAXIS1 and CENTERAXIS2 are used to center the subarray readout on the target spectrum, which will be displaced from the direct image of the target, in agreement with programs 16039, 16695, and 17082. We match the subarray size of the science exposures. We use FLASH=20 to meet the nominal count level. 18140( 3) - 15-Dec-2025 13:48:25 - [ 61] Exposures ------------------------------------------------------------------------------------------------------------------------------------ Exp | Target | Instr | Oper. | Aper |Spectral|Central| Optional |Num| Time | Special Num | Name | Config | Mode | or FOV |Element |Waveln.| Parameters |Exp| (Total) | Requirements ------------------------------------------------------------------------------------------------------------------------------------ ------------------------------------------------------------------------------------------------------------------------------------ 2 NAME-PROXIM WFC3/UVI ACCUM UVIS G280 FLASH=16, SIZEAXIS1=2000, 27 38 S (1026 POS TARG null, -50 A-CENTAURI S SIZEAXIS2=300, S) CENTERAXIS1=2136, CENTERAXIS2=1216 Comments: With exposure time of 40 second, we remain below 50% saturation (w/ saturation at 103 seconds) (with a maximum SNR of about 500 at about 7500 Angstrom), while remaining short enough for decent time-resolution of the flaring event. We also add a FLASH of 16, which when combined with the natural background of about 4 e- per exposure will result in >20 e- and better CTE. Nominal "UVIS" aperture is ~10" above the chip gap on chip 1; a Y-postarg of about -50" places the target near the center of subarray on chip 2. SIZEAXIS1=2000 and SIZEAXIS2=300 are used to minimize data volume, while CENTERAXIS1 and CENTERAXIS2 are used to center the subarray readout on the zeroth order of G280 spectrum. These parameters are based upon similar observations obtained successfully in GOs 13574 and 15288 but have been adjusted to better center the zeroth order spectrum on the sub-array (as done successfully for 16039). ------------------------------------------------------------------------------------------------------------------------------------ 3 BIAS WFC3/UVI ACCUM UVIS DEF SIZEAXIS1=2000, SIZEAXIS2=300, 4 0.0 S (0 S CENTERAXIS1=2136, S) CENTERAXIS2=1216 ------------------------------------------------------------------------------------------------------------------------------------ Sub Exposures ------------------------------------------------------------------------------------------------------------------------------------ Target | Exp |Instr | Oper. | Aper |Spectral|Cent.|Primary |Secondary |Iteration |CR-SPLIT |Orbit |Duration Name | Num |Config | Mode | or FOV |Element |Wave.|Pattern Pos |Pattern Pos |Num |Num |Number | ------------------------------------------------------------------------------------------------------------------------------------ NAME-PROXIMA-CENTAU 1 WFC3/UVI ACCUM G280-REF F300X none none none none 1 N/A RI S NAME-PROXIMA-CENTAU 2 WFC3/UVI ACCUM UVIS G280 none none 1 none 1 N/A RI S 18140( 3) - 15-Dec-2025 13:48:25 - [ 62] Sub Exposures ------------------------------------------------------------------------------------------------------------------------------------ Target | Exp |Instr | Oper. | Aper |Spectral|Cent.|Primary |Secondary |Iteration |CR-SPLIT |Orbit |Duration Name | Num |Config | Mode | or FOV |Element |Wave.|Pattern Pos |Pattern Pos |Num |Num |Number | ------------------------------------------------------------------------------------------------------------------------------------ NAME-PROXIMA-CENTAU 2 WFC3/UVI ACCUM UVIS G280 none none 2 none 1 N/A RI S NAME-PROXIMA-CENTAU 2 WFC3/UVI ACCUM UVIS G280 none none 3 none 1 N/A RI S NAME-PROXIMA-CENTAU 2 WFC3/UVI ACCUM UVIS G280 none none 4 none 1 N/A RI S NAME-PROXIMA-CENTAU 2 WFC3/UVI ACCUM UVIS G280 none none 5 none 1 N/A RI S NAME-PROXIMA-CENTAU 2 WFC3/UVI ACCUM UVIS G280 none none 6 none 1 N/A RI S NAME-PROXIMA-CENTAU 2 WFC3/UVI ACCUM UVIS G280 none none 7 none 1 N/A RI S NAME-PROXIMA-CENTAU 2 WFC3/UVI ACCUM UVIS G280 none none 8 none 1 N/A RI S NAME-PROXIMA-CENTAU 2 WFC3/UVI ACCUM UVIS G280 none none 9 none 1 N/A RI S NAME-PROXIMA-CENTAU 2 WFC3/UVI ACCUM UVIS G280 none none 10 none 1 N/A RI S NAME-PROXIMA-CENTAU 2 WFC3/UVI ACCUM UVIS G280 none none 11 none 1 N/A RI S NAME-PROXIMA-CENTAU 2 WFC3/UVI ACCUM UVIS G280 none none 12 none 1 N/A RI S NAME-PROXIMA-CENTAU 2 WFC3/UVI ACCUM UVIS G280 none none 13 none 1 N/A RI S NAME-PROXIMA-CENTAU 2 WFC3/UVI ACCUM UVIS G280 none none 14 none 1 N/A RI S NAME-PROXIMA-CENTAU 2 WFC3/UVI ACCUM UVIS G280 none none 15 none 1 N/A RI S NAME-PROXIMA-CENTAU 2 WFC3/UVI ACCUM UVIS G280 none none 16 none 1 N/A RI S NAME-PROXIMA-CENTAU 2 WFC3/UVI ACCUM UVIS G280 none none 17 none 1 N/A RI S NAME-PROXIMA-CENTAU 2 WFC3/UVI ACCUM UVIS G280 none none 18 none 1 N/A RI S NAME-PROXIMA-CENTAU 2 WFC3/UVI ACCUM UVIS G280 none none 19 none 1 N/A RI S NAME-PROXIMA-CENTAU 2 WFC3/UVI ACCUM UVIS G280 none none 20 none 1 N/A RI S NAME-PROXIMA-CENTAU 2 WFC3/UVI ACCUM UVIS G280 none none 21 none 1 N/A RI S NAME-PROXIMA-CENTAU 2 WFC3/UVI ACCUM UVIS G280 none none 22 none 1 N/A RI S NAME-PROXIMA-CENTAU 2 WFC3/UVI ACCUM UVIS G280 none none 23 none 1 N/A RI S NAME-PROXIMA-CENTAU 2 WFC3/UVI ACCUM UVIS G280 none none 24 none 1 N/A RI S NAME-PROXIMA-CENTAU 2 WFC3/UVI ACCUM UVIS G280 none none 25 none 1 N/A RI S 18140( 3) - 15-Dec-2025 13:48:25 - [ 63] Sub Exposures ------------------------------------------------------------------------------------------------------------------------------------ Target | Exp |Instr | Oper. | Aper |Spectral|Cent.|Primary |Secondary |Iteration |CR-SPLIT |Orbit |Duration Name | Num |Config | Mode | or FOV |Element |Wave.|Pattern Pos |Pattern Pos |Num |Num |Number | ------------------------------------------------------------------------------------------------------------------------------------ NAME-PROXIMA-CENTAU 2 WFC3/UVI ACCUM UVIS G280 none none 26 none 1 N/A RI S NAME-PROXIMA-CENTAU 2 WFC3/UVI ACCUM UVIS G280 none none 27 none 1 N/A RI S BIAS 3 WFC3/UVI ACCUM UVIS DEF none none 1 none 1 N/A S BIAS 3 WFC3/UVI ACCUM UVIS DEF none none 2 none 1 N/A S BIAS 3 WFC3/UVI ACCUM UVIS DEF none none 3 none 1 N/A S BIAS 3 WFC3/UVI ACCUM UVIS DEF none none 4 none 1 N/A S 18140( 3) - 15-Dec-2025 13:48:25 - [ 64] Visit: 16 Visit Requirements: ORIENT 0D TO 20 D; ORIENT 50D TO 120 D; ORIENT 180D TO 200 D; ORIENT 230D TO 300 D On Hold Comments: Additional Comments: The optional parameters SIZEAXIS1=2000 and SIZEAXIS2=300 are used for all exposures to minimize the data volume and hence time lost to buffer dumps. This is fine for the data that needs to be obtained because the spectum will occupy only a narrow swath of pixel rows within the field. This also requires the use of optional parameters CENTERAXIS1 and CENTERAXIS2 in order to "steer" the location of the subarray readout so that it is centered on the target spectrum. If we were positioning on chip 1 we could set CENTERAXIS2=TARGET. However, for the field center (nominal "UVIS" aperture) location on chip 2, we cannot center the subarray on the target because this would cause the subarray to extend into the chip gap, so we hardwire CENTERAXIS1=2136 and CENTERAXIS2=1216, which is intended to put the vertical center of the subarray on the zeroth order of the target spectrum. Chip 2 biases are taken at the end of the visit because the grism exposures use custom subarrays, which will not have matching biases from the WFC3 bias calibration program. For each visit we have phase constraints around the event of the planetary transit, both the orbital period of the planet and the phasing needed are placed on the target acq exposure. To avoid any contamination by several dim, nearby stars, we have placed Orient Ranges for the observations to reach our science goals. This results in ~15 transit opportunities for the UVIS observations in the coming months. Exposures ------------------------------------------------------------------------------------------------------------------------------------ Exp | Target | Instr | Oper. | Aper |Spectral|Central| Optional |Num| Time | Special Num | Name | Config | Mode | or FOV |Element |Waveln.| Parameters |Exp| (Total) | Requirements ------------------------------------------------------------------------------------------------------------------------------------ 1 NAME-PROXIM WFC3/UVI ACCUM G280-REF F300X FLASH=20, CENTERAXIS1=2136, 1 19 S (19 POS TARG null, -50; SEQ A-CENTAURI S CENTERAXIS2=1216, S) 1-3 NON-INT SIZEAXIS1=2000, SIZEAXIS2=300 Comments: For the reference image ("filter acq"), saturation in 259 seconds. 19.3 seconds gives SNR of 150. The nominal "UVIS" aperture is ~10" above the chip gap on chip 1; a Y-postarg of about -50" places the target near the center of subarray on chip 2, at an approximate XY position of (2048, 1024). CENTERAXIS1 and CENTERAXIS2 are used to center the subarray readout on the target spectrum, which will be displaced from the direct image of the target, in agreement with programs 16039, 16695, and 17082. We match the subarray size of the science exposures. We use FLASH=20 to meet the nominal count level. 18140( 3) - 15-Dec-2025 13:48:25 - [ 65] Exposures ------------------------------------------------------------------------------------------------------------------------------------ Exp | Target | Instr | Oper. | Aper |Spectral|Central| Optional |Num| Time | Special Num | Name | Config | Mode | or FOV |Element |Waveln.| Parameters |Exp| (Total) | Requirements ------------------------------------------------------------------------------------------------------------------------------------ ------------------------------------------------------------------------------------------------------------------------------------ 2 NAME-PROXIM WFC3/UVI ACCUM UVIS G280 FLASH=16, SIZEAXIS1=2000, 27 38 S (1026 POS TARG null, -50 A-CENTAURI S SIZEAXIS2=300, S) CENTERAXIS1=2136, CENTERAXIS2=1216 Comments: With exposure time of 40 second, we remain below 50% saturation (w/ saturation at 103 seconds) (with a maximum SNR of about 500 at about 7500 Angstrom), while remaining short enough for decent time-resolution of the flaring event. We also add a FLASH of 16, which when combined with the natural background of about 4 e- per exposure will result in >20 e- and better CTE. Nominal "UVIS" aperture is ~10" above the chip gap on chip 1; a Y-postarg of about -50" places the target near the center of subarray on chip 2. SIZEAXIS1=2000 and SIZEAXIS2=300 are used to minimize data volume, while CENTERAXIS1 and CENTERAXIS2 are used to center the subarray readout on the zeroth order of G280 spectrum. These parameters are based upon similar observations obtained successfully in GOs 13574 and 15288 but have been adjusted to better center the zeroth order spectrum on the sub-array (as done successfully for 16039). ------------------------------------------------------------------------------------------------------------------------------------ 3 BIAS WFC3/UVI ACCUM UVIS DEF SIZEAXIS1=2000, SIZEAXIS2=300, 4 0.0 S (0 S CENTERAXIS1=2136, S) CENTERAXIS2=1216 ------------------------------------------------------------------------------------------------------------------------------------ Sub Exposures ------------------------------------------------------------------------------------------------------------------------------------ Target | Exp |Instr | Oper. | Aper |Spectral|Cent.|Primary |Secondary |Iteration |CR-SPLIT |Orbit |Duration Name | Num |Config | Mode | or FOV |Element |Wave.|Pattern Pos |Pattern Pos |Num |Num |Number | ------------------------------------------------------------------------------------------------------------------------------------ NAME-PROXIMA-CENTAU 1 WFC3/UVI ACCUM G280-REF F300X none none none none 1 N/A RI S NAME-PROXIMA-CENTAU 2 WFC3/UVI ACCUM UVIS G280 none none 1 none 1 N/A RI S 18140( 3) - 15-Dec-2025 13:48:25 - [ 66] Sub Exposures ------------------------------------------------------------------------------------------------------------------------------------ Target | Exp |Instr | Oper. | Aper |Spectral|Cent.|Primary |Secondary |Iteration |CR-SPLIT |Orbit |Duration Name | Num |Config | Mode | or FOV |Element |Wave.|Pattern Pos |Pattern Pos |Num |Num |Number | ------------------------------------------------------------------------------------------------------------------------------------ NAME-PROXIMA-CENTAU 2 WFC3/UVI ACCUM UVIS G280 none none 2 none 1 N/A RI S NAME-PROXIMA-CENTAU 2 WFC3/UVI ACCUM UVIS G280 none none 3 none 1 N/A RI S NAME-PROXIMA-CENTAU 2 WFC3/UVI ACCUM UVIS G280 none none 4 none 1 N/A RI S NAME-PROXIMA-CENTAU 2 WFC3/UVI ACCUM UVIS G280 none none 5 none 1 N/A RI S NAME-PROXIMA-CENTAU 2 WFC3/UVI ACCUM UVIS G280 none none 6 none 1 N/A RI S NAME-PROXIMA-CENTAU 2 WFC3/UVI ACCUM UVIS G280 none none 7 none 1 N/A RI S NAME-PROXIMA-CENTAU 2 WFC3/UVI ACCUM UVIS G280 none none 8 none 1 N/A RI S NAME-PROXIMA-CENTAU 2 WFC3/UVI ACCUM UVIS G280 none none 9 none 1 N/A RI S NAME-PROXIMA-CENTAU 2 WFC3/UVI ACCUM UVIS G280 none none 10 none 1 N/A RI S NAME-PROXIMA-CENTAU 2 WFC3/UVI ACCUM UVIS G280 none none 11 none 1 N/A RI S NAME-PROXIMA-CENTAU 2 WFC3/UVI ACCUM UVIS G280 none none 12 none 1 N/A RI S NAME-PROXIMA-CENTAU 2 WFC3/UVI ACCUM UVIS G280 none none 13 none 1 N/A RI S NAME-PROXIMA-CENTAU 2 WFC3/UVI ACCUM UVIS G280 none none 14 none 1 N/A RI S NAME-PROXIMA-CENTAU 2 WFC3/UVI ACCUM UVIS G280 none none 15 none 1 N/A RI S NAME-PROXIMA-CENTAU 2 WFC3/UVI ACCUM UVIS G280 none none 16 none 1 N/A RI S NAME-PROXIMA-CENTAU 2 WFC3/UVI ACCUM UVIS G280 none none 17 none 1 N/A RI S NAME-PROXIMA-CENTAU 2 WFC3/UVI ACCUM UVIS G280 none none 18 none 1 N/A RI S NAME-PROXIMA-CENTAU 2 WFC3/UVI ACCUM UVIS G280 none none 19 none 1 N/A RI S NAME-PROXIMA-CENTAU 2 WFC3/UVI ACCUM UVIS G280 none none 20 none 1 N/A RI S NAME-PROXIMA-CENTAU 2 WFC3/UVI ACCUM UVIS G280 none none 21 none 1 N/A RI S NAME-PROXIMA-CENTAU 2 WFC3/UVI ACCUM UVIS G280 none none 22 none 1 N/A RI S NAME-PROXIMA-CENTAU 2 WFC3/UVI ACCUM UVIS G280 none none 23 none 1 N/A RI S NAME-PROXIMA-CENTAU 2 WFC3/UVI ACCUM UVIS G280 none none 24 none 1 N/A RI S NAME-PROXIMA-CENTAU 2 WFC3/UVI ACCUM UVIS G280 none none 25 none 1 N/A RI S 18140( 3) - 15-Dec-2025 13:48:25 - [ 67] Sub Exposures ------------------------------------------------------------------------------------------------------------------------------------ Target | Exp |Instr | Oper. | Aper |Spectral|Cent.|Primary |Secondary |Iteration |CR-SPLIT |Orbit |Duration Name | Num |Config | Mode | or FOV |Element |Wave.|Pattern Pos |Pattern Pos |Num |Num |Number | ------------------------------------------------------------------------------------------------------------------------------------ NAME-PROXIMA-CENTAU 2 WFC3/UVI ACCUM UVIS G280 none none 26 none 1 N/A RI S NAME-PROXIMA-CENTAU 2 WFC3/UVI ACCUM UVIS G280 none none 27 none 1 N/A RI S BIAS 3 WFC3/UVI ACCUM UVIS DEF none none 1 none 1 N/A S BIAS 3 WFC3/UVI ACCUM UVIS DEF none none 2 none 1 N/A S BIAS 3 WFC3/UVI ACCUM UVIS DEF none none 3 none 1 N/A S BIAS 3 WFC3/UVI ACCUM UVIS DEF none none 4 none 1 N/A S 18140( 3) - 15-Dec-2025 13:48:25 - [ 68] Visit: 17 Visit Requirements: ORIENT 0D TO 20 D; ORIENT 50D TO 120 D; ORIENT 180D TO 200 D; ORIENT 230D TO 300 D On Hold Comments: Additional Comments: The optional parameters SIZEAXIS1=2000 and SIZEAXIS2=300 are used for all exposures to minimize the data volume and hence time lost to buffer dumps. This is fine for the data that needs to be obtained because the spectum will occupy only a narrow swath of pixel rows within the field. This also requires the use of optional parameters CENTERAXIS1 and CENTERAXIS2 in order to "steer" the location of the subarray readout so that it is centered on the target spectrum. If we were positioning on chip 1 we could set CENTERAXIS2=TARGET. However, for the field center (nominal "UVIS" aperture) location on chip 2, we cannot center the subarray on the target because this would cause the subarray to extend into the chip gap, so we hardwire CENTERAXIS1=2136 and CENTERAXIS2=1216, which is intended to put the vertical center of the subarray on the zeroth order of the target spectrum. Chip 2 biases are taken at the end of the visit because the grism exposures use custom subarrays, which will not have matching biases from the WFC3 bias calibration program. For each visit we have phase constraints around the event of the planetary transit, both the orbital period of the planet and the phasing needed are placed on the target acq exposure. To avoid any contamination by several dim, nearby stars, we have placed Orient Ranges for the observations to reach our science goals. This results in ~15 transit opportunities for the UVIS observations in the coming months. Exposures ------------------------------------------------------------------------------------------------------------------------------------ Exp | Target | Instr | Oper. | Aper |Spectral|Central| Optional |Num| Time | Special Num | Name | Config | Mode | or FOV |Element |Waveln.| Parameters |Exp| (Total) | Requirements ------------------------------------------------------------------------------------------------------------------------------------ 1 NAME-PROXIM WFC3/UVI ACCUM G280-REF F300X FLASH=20, CENTERAXIS1=2136, 1 19 S (19 POS TARG null, -50; SEQ A-CENTAURI S CENTERAXIS2=1216, S) 1-3 NON-INT SIZEAXIS1=2000, SIZEAXIS2=300 Comments: For the reference image ("filter acq"), saturation in 259 seconds. 19.3 seconds gives SNR of 150. The nominal "UVIS" aperture is ~10" above the chip gap on chip 1; a Y-postarg of about -50" places the target near the center of subarray on chip 2, at an approximate XY position of (2048, 1024). CENTERAXIS1 and CENTERAXIS2 are used to center the subarray readout on the target spectrum, which will be displaced from the direct image of the target, in agreement with programs 16039, 16695, and 17082. We match the subarray size of the science exposures. We use FLASH=20 to meet the nominal count level. 18140( 3) - 15-Dec-2025 13:48:25 - [ 69] Exposures ------------------------------------------------------------------------------------------------------------------------------------ Exp | Target | Instr | Oper. | Aper |Spectral|Central| Optional |Num| Time | Special Num | Name | Config | Mode | or FOV |Element |Waveln.| Parameters |Exp| (Total) | Requirements ------------------------------------------------------------------------------------------------------------------------------------ ------------------------------------------------------------------------------------------------------------------------------------ 2 NAME-PROXIM WFC3/UVI ACCUM UVIS G280 FLASH=16, SIZEAXIS1=2000, 27 38 S (1026 POS TARG null, -50 A-CENTAURI S SIZEAXIS2=300, S) CENTERAXIS1=2136, CENTERAXIS2=1216 Comments: With exposure time of 40 second, we remain below 50% saturation (w/ saturation at 103 seconds) (with a maximum SNR of about 500 at about 7500 Angstrom), while remaining short enough for decent time-resolution of the flaring event. We also add a FLASH of 16, which when combined with the natural background of about 4 e- per exposure will result in >20 e- and better CTE. Nominal "UVIS" aperture is ~10" above the chip gap on chip 1; a Y-postarg of about -50" places the target near the center of subarray on chip 2. SIZEAXIS1=2000 and SIZEAXIS2=300 are used to minimize data volume, while CENTERAXIS1 and CENTERAXIS2 are used to center the subarray readout on the zeroth order of G280 spectrum. These parameters are based upon similar observations obtained successfully in GOs 13574 and 15288 but have been adjusted to better center the zeroth order spectrum on the sub-array (as done successfully for 16039). ------------------------------------------------------------------------------------------------------------------------------------ 3 BIAS WFC3/UVI ACCUM UVIS DEF SIZEAXIS1=2000, SIZEAXIS2=300, 4 0.0 S (0 S CENTERAXIS1=2136, S) CENTERAXIS2=1216 ------------------------------------------------------------------------------------------------------------------------------------ Sub Exposures ------------------------------------------------------------------------------------------------------------------------------------ Target | Exp |Instr | Oper. | Aper |Spectral|Cent.|Primary |Secondary |Iteration |CR-SPLIT |Orbit |Duration Name | Num |Config | Mode | or FOV |Element |Wave.|Pattern Pos |Pattern Pos |Num |Num |Number | ------------------------------------------------------------------------------------------------------------------------------------ NAME-PROXIMA-CENTAU 1 WFC3/UVI ACCUM G280-REF F300X none none none none 1 N/A RI S NAME-PROXIMA-CENTAU 2 WFC3/UVI ACCUM UVIS G280 none none 1 none 1 N/A RI S 18140( 3) - 15-Dec-2025 13:48:25 - [ 70] Sub Exposures ------------------------------------------------------------------------------------------------------------------------------------ Target | Exp |Instr | Oper. | Aper |Spectral|Cent.|Primary |Secondary |Iteration |CR-SPLIT |Orbit |Duration Name | Num |Config | Mode | or FOV |Element |Wave.|Pattern Pos |Pattern Pos |Num |Num |Number | ------------------------------------------------------------------------------------------------------------------------------------ NAME-PROXIMA-CENTAU 2 WFC3/UVI ACCUM UVIS G280 none none 2 none 1 N/A RI S NAME-PROXIMA-CENTAU 2 WFC3/UVI ACCUM UVIS G280 none none 3 none 1 N/A RI S NAME-PROXIMA-CENTAU 2 WFC3/UVI ACCUM UVIS G280 none none 4 none 1 N/A RI S NAME-PROXIMA-CENTAU 2 WFC3/UVI ACCUM UVIS G280 none none 5 none 1 N/A RI S NAME-PROXIMA-CENTAU 2 WFC3/UVI ACCUM UVIS G280 none none 6 none 1 N/A RI S NAME-PROXIMA-CENTAU 2 WFC3/UVI ACCUM UVIS G280 none none 7 none 1 N/A RI S NAME-PROXIMA-CENTAU 2 WFC3/UVI ACCUM UVIS G280 none none 8 none 1 N/A RI S NAME-PROXIMA-CENTAU 2 WFC3/UVI ACCUM UVIS G280 none none 9 none 1 N/A RI S NAME-PROXIMA-CENTAU 2 WFC3/UVI ACCUM UVIS G280 none none 10 none 1 N/A RI S NAME-PROXIMA-CENTAU 2 WFC3/UVI ACCUM UVIS G280 none none 11 none 1 N/A RI S NAME-PROXIMA-CENTAU 2 WFC3/UVI ACCUM UVIS G280 none none 12 none 1 N/A RI S NAME-PROXIMA-CENTAU 2 WFC3/UVI ACCUM UVIS G280 none none 13 none 1 N/A RI S NAME-PROXIMA-CENTAU 2 WFC3/UVI ACCUM UVIS G280 none none 14 none 1 N/A RI S NAME-PROXIMA-CENTAU 2 WFC3/UVI ACCUM UVIS G280 none none 15 none 1 N/A RI S NAME-PROXIMA-CENTAU 2 WFC3/UVI ACCUM UVIS G280 none none 16 none 1 N/A RI S NAME-PROXIMA-CENTAU 2 WFC3/UVI ACCUM UVIS G280 none none 17 none 1 N/A RI S NAME-PROXIMA-CENTAU 2 WFC3/UVI ACCUM UVIS G280 none none 18 none 1 N/A RI S NAME-PROXIMA-CENTAU 2 WFC3/UVI ACCUM UVIS G280 none none 19 none 1 N/A RI S NAME-PROXIMA-CENTAU 2 WFC3/UVI ACCUM UVIS G280 none none 20 none 1 N/A RI S NAME-PROXIMA-CENTAU 2 WFC3/UVI ACCUM UVIS G280 none none 21 none 1 N/A RI S NAME-PROXIMA-CENTAU 2 WFC3/UVI ACCUM UVIS G280 none none 22 none 1 N/A RI S NAME-PROXIMA-CENTAU 2 WFC3/UVI ACCUM UVIS G280 none none 23 none 1 N/A RI S NAME-PROXIMA-CENTAU 2 WFC3/UVI ACCUM UVIS G280 none none 24 none 1 N/A RI S NAME-PROXIMA-CENTAU 2 WFC3/UVI ACCUM UVIS G280 none none 25 none 1 N/A RI S 18140( 3) - 15-Dec-2025 13:48:25 - [ 71] Sub Exposures ------------------------------------------------------------------------------------------------------------------------------------ Target | Exp |Instr | Oper. | Aper |Spectral|Cent.|Primary |Secondary |Iteration |CR-SPLIT |Orbit |Duration Name | Num |Config | Mode | or FOV |Element |Wave.|Pattern Pos |Pattern Pos |Num |Num |Number | ------------------------------------------------------------------------------------------------------------------------------------ NAME-PROXIMA-CENTAU 2 WFC3/UVI ACCUM UVIS G280 none none 26 none 1 N/A RI S NAME-PROXIMA-CENTAU 2 WFC3/UVI ACCUM UVIS G280 none none 27 none 1 N/A RI S BIAS 3 WFC3/UVI ACCUM UVIS DEF none none 1 none 1 N/A S BIAS 3 WFC3/UVI ACCUM UVIS DEF none none 2 none 1 N/A S BIAS 3 WFC3/UVI ACCUM UVIS DEF none none 3 none 1 N/A S BIAS 3 WFC3/UVI ACCUM UVIS DEF none none 4 none 1 N/A S 18140( 3) - 15-Dec-2025 13:48:25 - [ 72] Visit: 18 Visit Requirements: ORIENT 0D TO 20 D; ORIENT 50D TO 120 D; ORIENT 180D TO 200 D; ORIENT 230D TO 300 D On Hold Comments: Additional Comments: The optional parameters SIZEAXIS1=2000 and SIZEAXIS2=300 are used for all exposures to minimize the data volume and hence time lost to buffer dumps. This is fine for the data that needs to be obtained because the spectum will occupy only a narrow swath of pixel rows within the field. This also requires the use of optional parameters CENTERAXIS1 and CENTERAXIS2 in order to "steer" the location of the subarray readout so that it is centered on the target spectrum. If we were positioning on chip 1 we could set CENTERAXIS2=TARGET. However, for the field center (nominal "UVIS" aperture) location on chip 2, we cannot center the subarray on the target because this would cause the subarray to extend into the chip gap, so we hardwire CENTERAXIS1=2136 and CENTERAXIS2=1216, which is intended to put the vertical center of the subarray on the zeroth order of the target spectrum. Chip 2 biases are taken at the end of the visit because the grism exposures use custom subarrays, which will not have matching biases from the WFC3 bias calibration program. For each visit we have phase constraints around the event of the planetary transit, both the orbital period of the planet and the phasing needed are placed on the target acq exposure. To avoid any contamination by several dim, nearby stars, we have placed Orient Ranges for the observations to reach our science goals. This results in ~15 transit opportunities for the UVIS observations in the coming months. Exposures ------------------------------------------------------------------------------------------------------------------------------------ Exp | Target | Instr | Oper. | Aper |Spectral|Central| Optional |Num| Time | Special Num | Name | Config | Mode | or FOV |Element |Waveln.| Parameters |Exp| (Total) | Requirements ------------------------------------------------------------------------------------------------------------------------------------ 1 NAME-PROXIM WFC3/UVI ACCUM G280-REF F300X FLASH=20, CENTERAXIS1=2136, 1 19 S (19 POS TARG null, -50; SEQ A-CENTAURI S CENTERAXIS2=1216, S) 1-3 NON-INT SIZEAXIS1=2000, SIZEAXIS2=300 Comments: For the reference image ("filter acq"), saturation in 259 seconds. 19.3 seconds gives SNR of 150. The nominal "UVIS" aperture is ~10" above the chip gap on chip 1; a Y-postarg of about -50" places the target near the center of subarray on chip 2, at an approximate XY position of (2048, 1024). CENTERAXIS1 and CENTERAXIS2 are used to center the subarray readout on the target spectrum, which will be displaced from the direct image of the target, in agreement with programs 16039, 16695, and 17082. We match the subarray size of the science exposures. We use FLASH=20 to meet the nominal count level. 18140( 3) - 15-Dec-2025 13:48:25 - [ 73] Exposures ------------------------------------------------------------------------------------------------------------------------------------ Exp | Target | Instr | Oper. | Aper |Spectral|Central| Optional |Num| Time | Special Num | Name | Config | Mode | or FOV |Element |Waveln.| Parameters |Exp| (Total) | Requirements ------------------------------------------------------------------------------------------------------------------------------------ ------------------------------------------------------------------------------------------------------------------------------------ 2 NAME-PROXIM WFC3/UVI ACCUM UVIS G280 FLASH=16, SIZEAXIS1=2000, 27 38 S (1026 POS TARG null, -50 A-CENTAURI S SIZEAXIS2=300, S) CENTERAXIS1=2136, CENTERAXIS2=1216 Comments: With exposure time of 40 second, we remain below 50% saturation (w/ saturation at 103 seconds) (with a maximum SNR of about 500 at about 7500 Angstrom), while remaining short enough for decent time-resolution of the flaring event. We also add a FLASH of 16, which when combined with the natural background of about 4 e- per exposure will result in >20 e- and better CTE. Nominal "UVIS" aperture is ~10" above the chip gap on chip 1; a Y-postarg of about -50" places the target near the center of subarray on chip 2. SIZEAXIS1=2000 and SIZEAXIS2=300 are used to minimize data volume, while CENTERAXIS1 and CENTERAXIS2 are used to center the subarray readout on the zeroth order of G280 spectrum. These parameters are based upon similar observations obtained successfully in GOs 13574 and 15288 but have been adjusted to better center the zeroth order spectrum on the sub-array (as done successfully for 16039). ------------------------------------------------------------------------------------------------------------------------------------ 3 BIAS WFC3/UVI ACCUM UVIS DEF SIZEAXIS1=2000, SIZEAXIS2=300, 4 0.0 S (0 S CENTERAXIS1=2136, S) CENTERAXIS2=1216 ------------------------------------------------------------------------------------------------------------------------------------ Sub Exposures ------------------------------------------------------------------------------------------------------------------------------------ Target | Exp |Instr | Oper. | Aper |Spectral|Cent.|Primary |Secondary |Iteration |CR-SPLIT |Orbit |Duration Name | Num |Config | Mode | or FOV |Element |Wave.|Pattern Pos |Pattern Pos |Num |Num |Number | ------------------------------------------------------------------------------------------------------------------------------------ NAME-PROXIMA-CENTAU 1 WFC3/UVI ACCUM G280-REF F300X none none none none 1 N/A RI S NAME-PROXIMA-CENTAU 2 WFC3/UVI ACCUM UVIS G280 none none 1 none 1 N/A RI S 18140( 3) - 15-Dec-2025 13:48:25 - [ 74] Sub Exposures ------------------------------------------------------------------------------------------------------------------------------------ Target | Exp |Instr | Oper. | Aper |Spectral|Cent.|Primary |Secondary |Iteration |CR-SPLIT |Orbit |Duration Name | Num |Config | Mode | or FOV |Element |Wave.|Pattern Pos |Pattern Pos |Num |Num |Number | ------------------------------------------------------------------------------------------------------------------------------------ NAME-PROXIMA-CENTAU 2 WFC3/UVI ACCUM UVIS G280 none none 2 none 1 N/A RI S NAME-PROXIMA-CENTAU 2 WFC3/UVI ACCUM UVIS G280 none none 3 none 1 N/A RI S NAME-PROXIMA-CENTAU 2 WFC3/UVI ACCUM UVIS G280 none none 4 none 1 N/A RI S NAME-PROXIMA-CENTAU 2 WFC3/UVI ACCUM UVIS G280 none none 5 none 1 N/A RI S NAME-PROXIMA-CENTAU 2 WFC3/UVI ACCUM UVIS G280 none none 6 none 1 N/A RI S NAME-PROXIMA-CENTAU 2 WFC3/UVI ACCUM UVIS G280 none none 7 none 1 N/A RI S NAME-PROXIMA-CENTAU 2 WFC3/UVI ACCUM UVIS G280 none none 8 none 1 N/A RI S NAME-PROXIMA-CENTAU 2 WFC3/UVI ACCUM UVIS G280 none none 9 none 1 N/A RI S NAME-PROXIMA-CENTAU 2 WFC3/UVI ACCUM UVIS G280 none none 10 none 1 N/A RI S NAME-PROXIMA-CENTAU 2 WFC3/UVI ACCUM UVIS G280 none none 11 none 1 N/A RI S NAME-PROXIMA-CENTAU 2 WFC3/UVI ACCUM UVIS G280 none none 12 none 1 N/A RI S NAME-PROXIMA-CENTAU 2 WFC3/UVI ACCUM UVIS G280 none none 13 none 1 N/A RI S NAME-PROXIMA-CENTAU 2 WFC3/UVI ACCUM UVIS G280 none none 14 none 1 N/A RI S NAME-PROXIMA-CENTAU 2 WFC3/UVI ACCUM UVIS G280 none none 15 none 1 N/A RI S NAME-PROXIMA-CENTAU 2 WFC3/UVI ACCUM UVIS G280 none none 16 none 1 N/A RI S NAME-PROXIMA-CENTAU 2 WFC3/UVI ACCUM UVIS G280 none none 17 none 1 N/A RI S NAME-PROXIMA-CENTAU 2 WFC3/UVI ACCUM UVIS G280 none none 18 none 1 N/A RI S NAME-PROXIMA-CENTAU 2 WFC3/UVI ACCUM UVIS G280 none none 19 none 1 N/A RI S NAME-PROXIMA-CENTAU 2 WFC3/UVI ACCUM UVIS G280 none none 20 none 1 N/A RI S NAME-PROXIMA-CENTAU 2 WFC3/UVI ACCUM UVIS G280 none none 21 none 1 N/A RI S NAME-PROXIMA-CENTAU 2 WFC3/UVI ACCUM UVIS G280 none none 22 none 1 N/A RI S NAME-PROXIMA-CENTAU 2 WFC3/UVI ACCUM UVIS G280 none none 23 none 1 N/A RI S NAME-PROXIMA-CENTAU 2 WFC3/UVI ACCUM UVIS G280 none none 24 none 1 N/A RI S NAME-PROXIMA-CENTAU 2 WFC3/UVI ACCUM UVIS G280 none none 25 none 1 N/A RI S 18140( 3) - 15-Dec-2025 13:48:25 - [ 75] Sub Exposures ------------------------------------------------------------------------------------------------------------------------------------ Target | Exp |Instr | Oper. | Aper |Spectral|Cent.|Primary |Secondary |Iteration |CR-SPLIT |Orbit |Duration Name | Num |Config | Mode | or FOV |Element |Wave.|Pattern Pos |Pattern Pos |Num |Num |Number | ------------------------------------------------------------------------------------------------------------------------------------ NAME-PROXIMA-CENTAU 2 WFC3/UVI ACCUM UVIS G280 none none 26 none 1 N/A RI S NAME-PROXIMA-CENTAU 2 WFC3/UVI ACCUM UVIS G280 none none 27 none 1 N/A RI S BIAS 3 WFC3/UVI ACCUM UVIS DEF none none 1 none 1 N/A S BIAS 3 WFC3/UVI ACCUM UVIS DEF none none 2 none 1 N/A S BIAS 3 WFC3/UVI ACCUM UVIS DEF none none 3 none 1 N/A S BIAS 3 WFC3/UVI ACCUM UVIS DEF none none 4 none 1 N/A S 18140( 3) - 15-Dec-2025 13:48:25 - [ 76] Visit: 19 Visit Requirements: ORIENT 0D TO 20 D; ORIENT 50D TO 120 D; ORIENT 180D TO 200 D; ORIENT 230D TO 300 D On Hold Comments: Additional Comments: The optional parameters SIZEAXIS1=2000 and SIZEAXIS2=300 are used for all exposures to minimize the data volume and hence time lost to buffer dumps. This is fine for the data that needs to be obtained because the spectum will occupy only a narrow swath of pixel rows within the field. This also requires the use of optional parameters CENTERAXIS1 and CENTERAXIS2 in order to "steer" the location of the subarray readout so that it is centered on the target spectrum. If we were positioning on chip 1 we could set CENTERAXIS2=TARGET. However, for the field center (nominal "UVIS" aperture) location on chip 2, we cannot center the subarray on the target because this would cause the subarray to extend into the chip gap, so we hardwire CENTERAXIS1=2136 and CENTERAXIS2=1216, which is intended to put the vertical center of the subarray on the zeroth order of the target spectrum. Chip 2 biases are taken at the end of the visit because the grism exposures use custom subarrays, which will not have matching biases from the WFC3 bias calibration program. For each visit we have phase constraints around the event of the planetary transit, both the orbital period of the planet and the phasing needed are placed on the target acq exposure. To avoid any contamination by several dim, nearby stars, we have placed Orient Ranges for the observations to reach our science goals. This results in ~15 transit opportunities for the UVIS observations in the coming months. Exposures ------------------------------------------------------------------------------------------------------------------------------------ Exp | Target | Instr | Oper. | Aper |Spectral|Central| Optional |Num| Time | Special Num | Name | Config | Mode | or FOV |Element |Waveln.| Parameters |Exp| (Total) | Requirements ------------------------------------------------------------------------------------------------------------------------------------ 1 NAME-PROXIM WFC3/UVI ACCUM G280-REF F300X FLASH=20, CENTERAXIS1=2136, 1 19 S (19 POS TARG null, -50; SEQ A-CENTAURI S CENTERAXIS2=1216, S) 1-3 NON-INT SIZEAXIS1=2000, SIZEAXIS2=300 Comments: For the reference image ("filter acq"), saturation in 259 seconds. 19.3 seconds gives SNR of 150. The nominal "UVIS" aperture is ~10" above the chip gap on chip 1; a Y-postarg of about -50" places the target near the center of subarray on chip 2, at an approximate XY position of (2048, 1024). CENTERAXIS1 and CENTERAXIS2 are used to center the subarray readout on the target spectrum, which will be displaced from the direct image of the target, in agreement with programs 16039, 16695, and 17082. We match the subarray size of the science exposures. We use FLASH=20 to meet the nominal count level. 18140( 3) - 15-Dec-2025 13:48:25 - [ 77] Exposures ------------------------------------------------------------------------------------------------------------------------------------ Exp | Target | Instr | Oper. | Aper |Spectral|Central| Optional |Num| Time | Special Num | Name | Config | Mode | or FOV |Element |Waveln.| Parameters |Exp| (Total) | Requirements ------------------------------------------------------------------------------------------------------------------------------------ ------------------------------------------------------------------------------------------------------------------------------------ 2 NAME-PROXIM WFC3/UVI ACCUM UVIS G280 FLASH=16, SIZEAXIS1=2000, 27 38 S (1026 POS TARG null, -50 A-CENTAURI S SIZEAXIS2=300, S) CENTERAXIS1=2136, CENTERAXIS2=1216 Comments: With exposure time of 40 second, we remain below 50% saturation (w/ saturation at 103 seconds) (with a maximum SNR of about 500 at about 7500 Angstrom), while remaining short enough for decent time-resolution of the flaring event. We also add a FLASH of 16, which when combined with the natural background of about 4 e- per exposure will result in >20 e- and better CTE. Nominal "UVIS" aperture is ~10" above the chip gap on chip 1; a Y-postarg of about -50" places the target near the center of subarray on chip 2. SIZEAXIS1=2000 and SIZEAXIS2=300 are used to minimize data volume, while CENTERAXIS1 and CENTERAXIS2 are used to center the subarray readout on the zeroth order of G280 spectrum. These parameters are based upon similar observations obtained successfully in GOs 13574 and 15288 but have been adjusted to better center the zeroth order spectrum on the sub-array (as done successfully for 16039). ------------------------------------------------------------------------------------------------------------------------------------ 3 BIAS WFC3/UVI ACCUM UVIS DEF SIZEAXIS1=2000, SIZEAXIS2=300, 4 0.0 S (0 S CENTERAXIS1=2136, S) CENTERAXIS2=1216 ------------------------------------------------------------------------------------------------------------------------------------ Sub Exposures ------------------------------------------------------------------------------------------------------------------------------------ Target | Exp |Instr | Oper. | Aper |Spectral|Cent.|Primary |Secondary |Iteration |CR-SPLIT |Orbit |Duration Name | Num |Config | Mode | or FOV |Element |Wave.|Pattern Pos |Pattern Pos |Num |Num |Number | ------------------------------------------------------------------------------------------------------------------------------------ NAME-PROXIMA-CENTAU 1 WFC3/UVI ACCUM G280-REF F300X none none none none 1 N/A RI S NAME-PROXIMA-CENTAU 2 WFC3/UVI ACCUM UVIS G280 none none 1 none 1 N/A RI S 18140( 3) - 15-Dec-2025 13:48:25 - [ 78] Sub Exposures ------------------------------------------------------------------------------------------------------------------------------------ Target | Exp |Instr | Oper. | Aper |Spectral|Cent.|Primary |Secondary |Iteration |CR-SPLIT |Orbit |Duration Name | Num |Config | Mode | or FOV |Element |Wave.|Pattern Pos |Pattern Pos |Num |Num |Number | ------------------------------------------------------------------------------------------------------------------------------------ NAME-PROXIMA-CENTAU 2 WFC3/UVI ACCUM UVIS G280 none none 2 none 1 N/A RI S NAME-PROXIMA-CENTAU 2 WFC3/UVI ACCUM UVIS G280 none none 3 none 1 N/A RI S NAME-PROXIMA-CENTAU 2 WFC3/UVI ACCUM UVIS G280 none none 4 none 1 N/A RI S NAME-PROXIMA-CENTAU 2 WFC3/UVI ACCUM UVIS G280 none none 5 none 1 N/A RI S NAME-PROXIMA-CENTAU 2 WFC3/UVI ACCUM UVIS G280 none none 6 none 1 N/A RI S NAME-PROXIMA-CENTAU 2 WFC3/UVI ACCUM UVIS G280 none none 7 none 1 N/A RI S NAME-PROXIMA-CENTAU 2 WFC3/UVI ACCUM UVIS G280 none none 8 none 1 N/A RI S NAME-PROXIMA-CENTAU 2 WFC3/UVI ACCUM UVIS G280 none none 9 none 1 N/A RI S NAME-PROXIMA-CENTAU 2 WFC3/UVI ACCUM UVIS G280 none none 10 none 1 N/A RI S NAME-PROXIMA-CENTAU 2 WFC3/UVI ACCUM UVIS G280 none none 11 none 1 N/A RI S NAME-PROXIMA-CENTAU 2 WFC3/UVI ACCUM UVIS G280 none none 12 none 1 N/A RI S NAME-PROXIMA-CENTAU 2 WFC3/UVI ACCUM UVIS G280 none none 13 none 1 N/A RI S NAME-PROXIMA-CENTAU 2 WFC3/UVI ACCUM UVIS G280 none none 14 none 1 N/A RI S NAME-PROXIMA-CENTAU 2 WFC3/UVI ACCUM UVIS G280 none none 15 none 1 N/A RI S NAME-PROXIMA-CENTAU 2 WFC3/UVI ACCUM UVIS G280 none none 16 none 1 N/A RI S NAME-PROXIMA-CENTAU 2 WFC3/UVI ACCUM UVIS G280 none none 17 none 1 N/A RI S NAME-PROXIMA-CENTAU 2 WFC3/UVI ACCUM UVIS G280 none none 18 none 1 N/A RI S NAME-PROXIMA-CENTAU 2 WFC3/UVI ACCUM UVIS G280 none none 19 none 1 N/A RI S NAME-PROXIMA-CENTAU 2 WFC3/UVI ACCUM UVIS G280 none none 20 none 1 N/A RI S NAME-PROXIMA-CENTAU 2 WFC3/UVI ACCUM UVIS G280 none none 21 none 1 N/A RI S NAME-PROXIMA-CENTAU 2 WFC3/UVI ACCUM UVIS G280 none none 22 none 1 N/A RI S NAME-PROXIMA-CENTAU 2 WFC3/UVI ACCUM UVIS G280 none none 23 none 1 N/A RI S NAME-PROXIMA-CENTAU 2 WFC3/UVI ACCUM UVIS G280 none none 24 none 1 N/A RI S NAME-PROXIMA-CENTAU 2 WFC3/UVI ACCUM UVIS G280 none none 25 none 1 N/A RI S 18140( 3) - 15-Dec-2025 13:48:25 - [ 79] Sub Exposures ------------------------------------------------------------------------------------------------------------------------------------ Target | Exp |Instr | Oper. | Aper |Spectral|Cent.|Primary |Secondary |Iteration |CR-SPLIT |Orbit |Duration Name | Num |Config | Mode | or FOV |Element |Wave.|Pattern Pos |Pattern Pos |Num |Num |Number | ------------------------------------------------------------------------------------------------------------------------------------ NAME-PROXIMA-CENTAU 2 WFC3/UVI ACCUM UVIS G280 none none 26 none 1 N/A RI S NAME-PROXIMA-CENTAU 2 WFC3/UVI ACCUM UVIS G280 none none 27 none 1 N/A RI S BIAS 3 WFC3/UVI ACCUM UVIS DEF none none 1 none 1 N/A S BIAS 3 WFC3/UVI ACCUM UVIS DEF none none 2 none 1 N/A S BIAS 3 WFC3/UVI ACCUM UVIS DEF none none 3 none 1 N/A S BIAS 3 WFC3/UVI ACCUM UVIS DEF none none 4 none 1 N/A S 18140( 3) - 15-Dec-2025 13:48:25 - [ 80] Visit: 20 Visit Requirements: ORIENT 0D TO 20 D; ORIENT 50D TO 120 D; ORIENT 180D TO 200 D; ORIENT 230D TO 300 D On Hold Comments: Additional Comments: The optional parameters SIZEAXIS1=2000 and SIZEAXIS2=300 are used for all exposures to minimize the data volume and hence time lost to buffer dumps. This is fine for the data that needs to be obtained because the spectum will occupy only a narrow swath of pixel rows within the field. This also requires the use of optional parameters CENTERAXIS1 and CENTERAXIS2 in order to "steer" the location of the subarray readout so that it is centered on the target spectrum. If we were positioning on chip 1 we could set CENTERAXIS2=TARGET. However, for the field center (nominal "UVIS" aperture) location on chip 2, we cannot center the subarray on the target because this would cause the subarray to extend into the chip gap, so we hardwire CENTERAXIS1=2136 and CENTERAXIS2=1216, which is intended to put the vertical center of the subarray on the zeroth order of the target spectrum. Chip 2 biases are taken at the end of the visit because the grism exposures use custom subarrays, which will not have matching biases from the WFC3 bias calibration program. For each visit we have phase constraints around the event of the planetary transit, both the orbital period of the planet and the phasing needed are placed on the target acq exposure. To avoid any contamination by several dim, nearby stars, we have placed Orient Ranges for the observations to reach our science goals. This results in ~15 transit opportunities for the UVIS observations in the coming months. Exposures ------------------------------------------------------------------------------------------------------------------------------------ Exp | Target | Instr | Oper. | Aper |Spectral|Central| Optional |Num| Time | Special Num | Name | Config | Mode | or FOV |Element |Waveln.| Parameters |Exp| (Total) | Requirements ------------------------------------------------------------------------------------------------------------------------------------ 1 NAME-PROXIM WFC3/UVI ACCUM G280-REF F300X FLASH=20, CENTERAXIS1=2136, 1 19 S (19 POS TARG null, -50; SEQ A-CENTAURI S CENTERAXIS2=1216, S) 1-3 NON-INT SIZEAXIS1=2000, SIZEAXIS2=300 Comments: For the reference image ("filter acq"), saturation in 259 seconds. 19.3 seconds gives SNR of 150. The nominal "UVIS" aperture is ~10" above the chip gap on chip 1; a Y-postarg of about -50" places the target near the center of subarray on chip 2, at an approximate XY position of (2048, 1024). CENTERAXIS1 and CENTERAXIS2 are used to center the subarray readout on the target spectrum, which will be displaced from the direct image of the target, in agreement with programs 16039, 16695, and 17082. We match the subarray size of the science exposures. We use FLASH=20 to meet the nominal count level. 18140( 3) - 15-Dec-2025 13:48:25 - [ 81] Exposures ------------------------------------------------------------------------------------------------------------------------------------ Exp | Target | Instr | Oper. | Aper |Spectral|Central| Optional |Num| Time | Special Num | Name | Config | Mode | or FOV |Element |Waveln.| Parameters |Exp| (Total) | Requirements ------------------------------------------------------------------------------------------------------------------------------------ ------------------------------------------------------------------------------------------------------------------------------------ 2 NAME-PROXIM WFC3/UVI ACCUM UVIS G280 FLASH=16, SIZEAXIS1=2000, 27 38 S (1026 POS TARG null, -50 A-CENTAURI S SIZEAXIS2=300, S) CENTERAXIS1=2136, CENTERAXIS2=1216 Comments: With exposure time of 40 second, we remain below 50% saturation (w/ saturation at 103 seconds) (with a maximum SNR of about 500 at about 7500 Angstrom), while remaining short enough for decent time-resolution of the flaring event. We also add a FLASH of 16, which when combined with the natural background of about 4 e- per exposure will result in >20 e- and better CTE. Nominal "UVIS" aperture is ~10" above the chip gap on chip 1; a Y-postarg of about -50" places the target near the center of subarray on chip 2. SIZEAXIS1=2000 and SIZEAXIS2=300 are used to minimize data volume, while CENTERAXIS1 and CENTERAXIS2 are used to center the subarray readout on the zeroth order of G280 spectrum. These parameters are based upon similar observations obtained successfully in GOs 13574 and 15288 but have been adjusted to better center the zeroth order spectrum on the sub-array (as done successfully for 16039). ------------------------------------------------------------------------------------------------------------------------------------ 3 BIAS WFC3/UVI ACCUM UVIS DEF SIZEAXIS1=2000, SIZEAXIS2=300, 4 0.0 S (0 S CENTERAXIS1=2136, S) CENTERAXIS2=1216 ------------------------------------------------------------------------------------------------------------------------------------ Sub Exposures ------------------------------------------------------------------------------------------------------------------------------------ Target | Exp |Instr | Oper. | Aper |Spectral|Cent.|Primary |Secondary |Iteration |CR-SPLIT |Orbit |Duration Name | Num |Config | Mode | or FOV |Element |Wave.|Pattern Pos |Pattern Pos |Num |Num |Number | ------------------------------------------------------------------------------------------------------------------------------------ NAME-PROXIMA-CENTAU 1 WFC3/UVI ACCUM G280-REF F300X none none none none 1 N/A RI S NAME-PROXIMA-CENTAU 2 WFC3/UVI ACCUM UVIS G280 none none 1 none 1 N/A RI S 18140( 3) - 15-Dec-2025 13:48:25 - [ 82] Sub Exposures ------------------------------------------------------------------------------------------------------------------------------------ Target | Exp |Instr | Oper. | Aper |Spectral|Cent.|Primary |Secondary |Iteration |CR-SPLIT |Orbit |Duration Name | Num |Config | Mode | or FOV |Element |Wave.|Pattern Pos |Pattern Pos |Num |Num |Number | ------------------------------------------------------------------------------------------------------------------------------------ NAME-PROXIMA-CENTAU 2 WFC3/UVI ACCUM UVIS G280 none none 2 none 1 N/A RI S NAME-PROXIMA-CENTAU 2 WFC3/UVI ACCUM UVIS G280 none none 3 none 1 N/A RI S NAME-PROXIMA-CENTAU 2 WFC3/UVI ACCUM UVIS G280 none none 4 none 1 N/A RI S NAME-PROXIMA-CENTAU 2 WFC3/UVI ACCUM UVIS G280 none none 5 none 1 N/A RI S NAME-PROXIMA-CENTAU 2 WFC3/UVI ACCUM UVIS G280 none none 6 none 1 N/A RI S NAME-PROXIMA-CENTAU 2 WFC3/UVI ACCUM UVIS G280 none none 7 none 1 N/A RI S NAME-PROXIMA-CENTAU 2 WFC3/UVI ACCUM UVIS G280 none none 8 none 1 N/A RI S NAME-PROXIMA-CENTAU 2 WFC3/UVI ACCUM UVIS G280 none none 9 none 1 N/A RI S NAME-PROXIMA-CENTAU 2 WFC3/UVI ACCUM UVIS G280 none none 10 none 1 N/A RI S NAME-PROXIMA-CENTAU 2 WFC3/UVI ACCUM UVIS G280 none none 11 none 1 N/A RI S NAME-PROXIMA-CENTAU 2 WFC3/UVI ACCUM UVIS G280 none none 12 none 1 N/A RI S NAME-PROXIMA-CENTAU 2 WFC3/UVI ACCUM UVIS G280 none none 13 none 1 N/A RI S NAME-PROXIMA-CENTAU 2 WFC3/UVI ACCUM UVIS G280 none none 14 none 1 N/A RI S NAME-PROXIMA-CENTAU 2 WFC3/UVI ACCUM UVIS G280 none none 15 none 1 N/A RI S NAME-PROXIMA-CENTAU 2 WFC3/UVI ACCUM UVIS G280 none none 16 none 1 N/A RI S NAME-PROXIMA-CENTAU 2 WFC3/UVI ACCUM UVIS G280 none none 17 none 1 N/A RI S NAME-PROXIMA-CENTAU 2 WFC3/UVI ACCUM UVIS G280 none none 18 none 1 N/A RI S NAME-PROXIMA-CENTAU 2 WFC3/UVI ACCUM UVIS G280 none none 19 none 1 N/A RI S NAME-PROXIMA-CENTAU 2 WFC3/UVI ACCUM UVIS G280 none none 20 none 1 N/A RI S NAME-PROXIMA-CENTAU 2 WFC3/UVI ACCUM UVIS G280 none none 21 none 1 N/A RI S NAME-PROXIMA-CENTAU 2 WFC3/UVI ACCUM UVIS G280 none none 22 none 1 N/A RI S NAME-PROXIMA-CENTAU 2 WFC3/UVI ACCUM UVIS G280 none none 23 none 1 N/A RI S NAME-PROXIMA-CENTAU 2 WFC3/UVI ACCUM UVIS G280 none none 24 none 1 N/A RI S NAME-PROXIMA-CENTAU 2 WFC3/UVI ACCUM UVIS G280 none none 25 none 1 N/A RI S 18140( 3) - 15-Dec-2025 13:48:25 - [ 83] Sub Exposures ------------------------------------------------------------------------------------------------------------------------------------ Target | Exp |Instr | Oper. | Aper |Spectral|Cent.|Primary |Secondary |Iteration |CR-SPLIT |Orbit |Duration Name | Num |Config | Mode | or FOV |Element |Wave.|Pattern Pos |Pattern Pos |Num |Num |Number | ------------------------------------------------------------------------------------------------------------------------------------ NAME-PROXIMA-CENTAU 2 WFC3/UVI ACCUM UVIS G280 none none 26 none 1 N/A RI S NAME-PROXIMA-CENTAU 2 WFC3/UVI ACCUM UVIS G280 none none 27 none 1 N/A RI S BIAS 3 WFC3/UVI ACCUM UVIS DEF none none 1 none 1 N/A S BIAS 3 WFC3/UVI ACCUM UVIS DEF none none 2 none 1 N/A S BIAS 3 WFC3/UVI ACCUM UVIS DEF none none 3 none 1 N/A S BIAS 3 WFC3/UVI ACCUM UVIS DEF none none 4 none 1 N/A S 18140( 3) - 15-Dec-2025 13:48:25 - [ 84] Visit: 21 Visit Requirements: ORIENT 0D TO 20 D; ORIENT 50D TO 120 D; ORIENT 180D TO 200 D; ORIENT 230D TO 300 D On Hold Comments: Additional Comments: The optional parameters SIZEAXIS1=2000 and SIZEAXIS2=300 are used for all exposures to minimize the data volume and hence time lost to buffer dumps. This is fine for the data that needs to be obtained because the spectum will occupy only a narrow swath of pixel rows within the field. This also requires the use of optional parameters CENTERAXIS1 and CENTERAXIS2 in order to "steer" the location of the subarray readout so that it is centered on the target spectrum. If we were positioning on chip 1 we could set CENTERAXIS2=TARGET. However, for the field center (nominal "UVIS" aperture) location on chip 2, we cannot center the subarray on the target because this would cause the subarray to extend into the chip gap, so we hardwire CENTERAXIS1=2136 and CENTERAXIS2=1216, which is intended to put the vertical center of the subarray on the zeroth order of the target spectrum. Chip 2 biases are taken at the end of the visit because the grism exposures use custom subarrays, which will not have matching biases from the WFC3 bias calibration program. For each visit we have phase constraints around the event of the planetary transit, both the orbital period of the planet and the phasing needed are placed on the target acq exposure. To avoid any contamination by several dim, nearby stars, we have placed Orient Ranges for the observations to reach our science goals. This results in ~15 transit opportunities for the UVIS observations in the coming months. Exposures ------------------------------------------------------------------------------------------------------------------------------------ Exp | Target | Instr | Oper. | Aper |Spectral|Central| Optional |Num| Time | Special Num | Name | Config | Mode | or FOV |Element |Waveln.| Parameters |Exp| (Total) | Requirements ------------------------------------------------------------------------------------------------------------------------------------ 1 NAME-PROXIM WFC3/UVI ACCUM G280-REF F300X FLASH=20, CENTERAXIS1=2136, 1 19 S (19 POS TARG null, -50; SEQ A-CENTAURI S CENTERAXIS2=1216, S) 1-3 NON-INT SIZEAXIS1=2000, SIZEAXIS2=300 Comments: For the reference image ("filter acq"), saturation in 259 seconds. 19.3 seconds gives SNR of 150. The nominal "UVIS" aperture is ~10" above the chip gap on chip 1; a Y-postarg of about -50" places the target near the center of subarray on chip 2, at an approximate XY position of (2048, 1024). CENTERAXIS1 and CENTERAXIS2 are used to center the subarray readout on the target spectrum, which will be displaced from the direct image of the target, in agreement with programs 16039, 16695, and 17082. We match the subarray size of the science exposures. We use FLASH=20 to meet the nominal count level. 18140( 3) - 15-Dec-2025 13:48:25 - [ 85] Exposures ------------------------------------------------------------------------------------------------------------------------------------ Exp | Target | Instr | Oper. | Aper |Spectral|Central| Optional |Num| Time | Special Num | Name | Config | Mode | or FOV |Element |Waveln.| Parameters |Exp| (Total) | Requirements ------------------------------------------------------------------------------------------------------------------------------------ ------------------------------------------------------------------------------------------------------------------------------------ 2 NAME-PROXIM WFC3/UVI ACCUM UVIS G280 FLASH=16, SIZEAXIS1=2000, 27 38 S (1026 POS TARG null, -50 A-CENTAURI S SIZEAXIS2=300, S) CENTERAXIS1=2136, CENTERAXIS2=1216 Comments: With exposure time of 40 second, we remain below 50% saturation (w/ saturation at 103 seconds) (with a maximum SNR of about 500 at about 7500 Angstrom), while remaining short enough for decent time-resolution of the flaring event. We also add a FLASH of 16, which when combined with the natural background of about 4 e- per exposure will result in >20 e- and better CTE. Nominal "UVIS" aperture is ~10" above the chip gap on chip 1; a Y-postarg of about -50" places the target near the center of subarray on chip 2. SIZEAXIS1=2000 and SIZEAXIS2=300 are used to minimize data volume, while CENTERAXIS1 and CENTERAXIS2 are used to center the subarray readout on the zeroth order of G280 spectrum. These parameters are based upon similar observations obtained successfully in GOs 13574 and 15288 but have been adjusted to better center the zeroth order spectrum on the sub-array (as done successfully for 16039). ------------------------------------------------------------------------------------------------------------------------------------ 3 BIAS WFC3/UVI ACCUM UVIS DEF SIZEAXIS1=2000, SIZEAXIS2=300, 4 0.0 S (0 S CENTERAXIS1=2136, S) CENTERAXIS2=1216 ------------------------------------------------------------------------------------------------------------------------------------ Sub Exposures ------------------------------------------------------------------------------------------------------------------------------------ Target | Exp |Instr | Oper. | Aper |Spectral|Cent.|Primary |Secondary |Iteration |CR-SPLIT |Orbit |Duration Name | Num |Config | Mode | or FOV |Element |Wave.|Pattern Pos |Pattern Pos |Num |Num |Number | ------------------------------------------------------------------------------------------------------------------------------------ NAME-PROXIMA-CENTAU 1 WFC3/UVI ACCUM G280-REF F300X none none none none 1 N/A RI S NAME-PROXIMA-CENTAU 2 WFC3/UVI ACCUM UVIS G280 none none 1 none 1 N/A RI S 18140( 3) - 15-Dec-2025 13:48:25 - [ 86] Sub Exposures ------------------------------------------------------------------------------------------------------------------------------------ Target | Exp |Instr | Oper. | Aper |Spectral|Cent.|Primary |Secondary |Iteration |CR-SPLIT |Orbit |Duration Name | Num |Config | Mode | or FOV |Element |Wave.|Pattern Pos |Pattern Pos |Num |Num |Number | ------------------------------------------------------------------------------------------------------------------------------------ NAME-PROXIMA-CENTAU 2 WFC3/UVI ACCUM UVIS G280 none none 2 none 1 N/A RI S NAME-PROXIMA-CENTAU 2 WFC3/UVI ACCUM UVIS G280 none none 3 none 1 N/A RI S NAME-PROXIMA-CENTAU 2 WFC3/UVI ACCUM UVIS G280 none none 4 none 1 N/A RI S NAME-PROXIMA-CENTAU 2 WFC3/UVI ACCUM UVIS G280 none none 5 none 1 N/A RI S NAME-PROXIMA-CENTAU 2 WFC3/UVI ACCUM UVIS G280 none none 6 none 1 N/A RI S NAME-PROXIMA-CENTAU 2 WFC3/UVI ACCUM UVIS G280 none none 7 none 1 N/A RI S NAME-PROXIMA-CENTAU 2 WFC3/UVI ACCUM UVIS G280 none none 8 none 1 N/A RI S NAME-PROXIMA-CENTAU 2 WFC3/UVI ACCUM UVIS G280 none none 9 none 1 N/A RI S NAME-PROXIMA-CENTAU 2 WFC3/UVI ACCUM UVIS G280 none none 10 none 1 N/A RI S NAME-PROXIMA-CENTAU 2 WFC3/UVI ACCUM UVIS G280 none none 11 none 1 N/A RI S NAME-PROXIMA-CENTAU 2 WFC3/UVI ACCUM UVIS G280 none none 12 none 1 N/A RI S NAME-PROXIMA-CENTAU 2 WFC3/UVI ACCUM UVIS G280 none none 13 none 1 N/A RI S NAME-PROXIMA-CENTAU 2 WFC3/UVI ACCUM UVIS G280 none none 14 none 1 N/A RI S NAME-PROXIMA-CENTAU 2 WFC3/UVI ACCUM UVIS G280 none none 15 none 1 N/A RI S NAME-PROXIMA-CENTAU 2 WFC3/UVI ACCUM UVIS G280 none none 16 none 1 N/A RI S NAME-PROXIMA-CENTAU 2 WFC3/UVI ACCUM UVIS G280 none none 17 none 1 N/A RI S NAME-PROXIMA-CENTAU 2 WFC3/UVI ACCUM UVIS G280 none none 18 none 1 N/A RI S NAME-PROXIMA-CENTAU 2 WFC3/UVI ACCUM UVIS G280 none none 19 none 1 N/A RI S NAME-PROXIMA-CENTAU 2 WFC3/UVI ACCUM UVIS G280 none none 20 none 1 N/A RI S NAME-PROXIMA-CENTAU 2 WFC3/UVI ACCUM UVIS G280 none none 21 none 1 N/A RI S NAME-PROXIMA-CENTAU 2 WFC3/UVI ACCUM UVIS G280 none none 22 none 1 N/A RI S NAME-PROXIMA-CENTAU 2 WFC3/UVI ACCUM UVIS G280 none none 23 none 1 N/A RI S NAME-PROXIMA-CENTAU 2 WFC3/UVI ACCUM UVIS G280 none none 24 none 1 N/A RI S NAME-PROXIMA-CENTAU 2 WFC3/UVI ACCUM UVIS G280 none none 25 none 1 N/A RI S 18140( 3) - 15-Dec-2025 13:48:25 - [ 87] Sub Exposures ------------------------------------------------------------------------------------------------------------------------------------ Target | Exp |Instr | Oper. | Aper |Spectral|Cent.|Primary |Secondary |Iteration |CR-SPLIT |Orbit |Duration Name | Num |Config | Mode | or FOV |Element |Wave.|Pattern Pos |Pattern Pos |Num |Num |Number | ------------------------------------------------------------------------------------------------------------------------------------ NAME-PROXIMA-CENTAU 2 WFC3/UVI ACCUM UVIS G280 none none 26 none 1 N/A RI S NAME-PROXIMA-CENTAU 2 WFC3/UVI ACCUM UVIS G280 none none 27 none 1 N/A RI S BIAS 3 WFC3/UVI ACCUM UVIS DEF none none 1 none 1 N/A S BIAS 3 WFC3/UVI ACCUM UVIS DEF none none 2 none 1 N/A S BIAS 3 WFC3/UVI ACCUM UVIS DEF none none 3 none 1 N/A S BIAS 3 WFC3/UVI ACCUM UVIS DEF none none 4 none 1 N/A S 18140( 3) - 15-Dec-2025 13:48:25 - [ 88] Visit: 22 Visit Requirements: ORIENT 0D TO 20 D; ORIENT 50D TO 120 D; ORIENT 180D TO 200 D; ORIENT 230D TO 300 D On Hold Comments: Additional Comments: The optional parameters SIZEAXIS1=2000 and SIZEAXIS2=300 are used for all exposures to minimize the data volume and hence time lost to buffer dumps. This is fine for the data that needs to be obtained because the spectum will occupy only a narrow swath of pixel rows within the field. This also requires the use of optional parameters CENTERAXIS1 and CENTERAXIS2 in order to "steer" the location of the subarray readout so that it is centered on the target spectrum. If we were positioning on chip 1 we could set CENTERAXIS2=TARGET. However, for the field center (nominal "UVIS" aperture) location on chip 2, we cannot center the subarray on the target because this would cause the subarray to extend into the chip gap, so we hardwire CENTERAXIS1=2136 and CENTERAXIS2=1216, which is intended to put the vertical center of the subarray on the zeroth order of the target spectrum. Chip 2 biases are taken at the end of the visit because the grism exposures use custom subarrays, which will not have matching biases from the WFC3 bias calibration program. For each visit we have phase constraints around the event of the planetary transit, both the orbital period of the planet and the phasing needed are placed on the target acq exposure. To avoid any contamination by several dim, nearby stars, we have placed Orient Ranges for the observations to reach our science goals. This results in ~15 transit opportunities for the UVIS observations in the coming months. Exposures ------------------------------------------------------------------------------------------------------------------------------------ Exp | Target | Instr | Oper. | Aper |Spectral|Central| Optional |Num| Time | Special Num | Name | Config | Mode | or FOV |Element |Waveln.| Parameters |Exp| (Total) | Requirements ------------------------------------------------------------------------------------------------------------------------------------ 1 NAME-PROXIM WFC3/UVI ACCUM G280-REF F300X FLASH=20, CENTERAXIS1=2136, 1 19 S (19 POS TARG null, -50; SEQ A-CENTAURI S CENTERAXIS2=1216, S) 1-3 NON-INT SIZEAXIS1=2000, SIZEAXIS2=300 Comments: For the reference image ("filter acq"), saturation in 259 seconds. 19.3 seconds gives SNR of 150. The nominal "UVIS" aperture is ~10" above the chip gap on chip 1; a Y-postarg of about -50" places the target near the center of subarray on chip 2, at an approximate XY position of (2048, 1024). CENTERAXIS1 and CENTERAXIS2 are used to center the subarray readout on the target spectrum, which will be displaced from the direct image of the target, in agreement with programs 16039, 16695, and 17082. We match the subarray size of the science exposures. We use FLASH=20 to meet the nominal count level. 18140( 3) - 15-Dec-2025 13:48:25 - [ 89] Exposures ------------------------------------------------------------------------------------------------------------------------------------ Exp | Target | Instr | Oper. | Aper |Spectral|Central| Optional |Num| Time | Special Num | Name | Config | Mode | or FOV |Element |Waveln.| Parameters |Exp| (Total) | Requirements ------------------------------------------------------------------------------------------------------------------------------------ ------------------------------------------------------------------------------------------------------------------------------------ 2 NAME-PROXIM WFC3/UVI ACCUM UVIS G280 FLASH=16, SIZEAXIS1=2000, 27 38 S (1026 POS TARG null, -50 A-CENTAURI S SIZEAXIS2=300, S) CENTERAXIS1=2136, CENTERAXIS2=1216 Comments: With exposure time of 40 second, we remain below 50% saturation (w/ saturation at 103 seconds) (with a maximum SNR of about 500 at about 7500 Angstrom), while remaining short enough for decent time-resolution of the flaring event. We also add a FLASH of 16, which when combined with the natural background of about 4 e- per exposure will result in >20 e- and better CTE. Nominal "UVIS" aperture is ~10" above the chip gap on chip 1; a Y-postarg of about -50" places the target near the center of subarray on chip 2. SIZEAXIS1=2000 and SIZEAXIS2=300 are used to minimize data volume, while CENTERAXIS1 and CENTERAXIS2 are used to center the subarray readout on the zeroth order of G280 spectrum. These parameters are based upon similar observations obtained successfully in GOs 13574 and 15288 but have been adjusted to better center the zeroth order spectrum on the sub-array (as done successfully for 16039). ------------------------------------------------------------------------------------------------------------------------------------ 3 BIAS WFC3/UVI ACCUM UVIS DEF SIZEAXIS1=2000, SIZEAXIS2=300, 4 0.0 S (0 S CENTERAXIS1=2136, S) CENTERAXIS2=1216 ------------------------------------------------------------------------------------------------------------------------------------ Sub Exposures ------------------------------------------------------------------------------------------------------------------------------------ Target | Exp |Instr | Oper. | Aper |Spectral|Cent.|Primary |Secondary |Iteration |CR-SPLIT |Orbit |Duration Name | Num |Config | Mode | or FOV |Element |Wave.|Pattern Pos |Pattern Pos |Num |Num |Number | ------------------------------------------------------------------------------------------------------------------------------------ NAME-PROXIMA-CENTAU 1 WFC3/UVI ACCUM G280-REF F300X none none none none 1 N/A RI S NAME-PROXIMA-CENTAU 2 WFC3/UVI ACCUM UVIS G280 none none 1 none 1 N/A RI S 18140( 3) - 15-Dec-2025 13:48:25 - [ 90] Sub Exposures ------------------------------------------------------------------------------------------------------------------------------------ Target | Exp |Instr | Oper. | Aper |Spectral|Cent.|Primary |Secondary |Iteration |CR-SPLIT |Orbit |Duration Name | Num |Config | Mode | or FOV |Element |Wave.|Pattern Pos |Pattern Pos |Num |Num |Number | ------------------------------------------------------------------------------------------------------------------------------------ NAME-PROXIMA-CENTAU 2 WFC3/UVI ACCUM UVIS G280 none none 2 none 1 N/A RI S NAME-PROXIMA-CENTAU 2 WFC3/UVI ACCUM UVIS G280 none none 3 none 1 N/A RI S NAME-PROXIMA-CENTAU 2 WFC3/UVI ACCUM UVIS G280 none none 4 none 1 N/A RI S NAME-PROXIMA-CENTAU 2 WFC3/UVI ACCUM UVIS G280 none none 5 none 1 N/A RI S NAME-PROXIMA-CENTAU 2 WFC3/UVI ACCUM UVIS G280 none none 6 none 1 N/A RI S NAME-PROXIMA-CENTAU 2 WFC3/UVI ACCUM UVIS G280 none none 7 none 1 N/A RI S NAME-PROXIMA-CENTAU 2 WFC3/UVI ACCUM UVIS G280 none none 8 none 1 N/A RI S NAME-PROXIMA-CENTAU 2 WFC3/UVI ACCUM UVIS G280 none none 9 none 1 N/A RI S NAME-PROXIMA-CENTAU 2 WFC3/UVI ACCUM UVIS G280 none none 10 none 1 N/A RI S NAME-PROXIMA-CENTAU 2 WFC3/UVI ACCUM UVIS G280 none none 11 none 1 N/A RI S NAME-PROXIMA-CENTAU 2 WFC3/UVI ACCUM UVIS G280 none none 12 none 1 N/A RI S NAME-PROXIMA-CENTAU 2 WFC3/UVI ACCUM UVIS G280 none none 13 none 1 N/A RI S NAME-PROXIMA-CENTAU 2 WFC3/UVI ACCUM UVIS G280 none none 14 none 1 N/A RI S NAME-PROXIMA-CENTAU 2 WFC3/UVI ACCUM UVIS G280 none none 15 none 1 N/A RI S NAME-PROXIMA-CENTAU 2 WFC3/UVI ACCUM UVIS G280 none none 16 none 1 N/A RI S NAME-PROXIMA-CENTAU 2 WFC3/UVI ACCUM UVIS G280 none none 17 none 1 N/A RI S NAME-PROXIMA-CENTAU 2 WFC3/UVI ACCUM UVIS G280 none none 18 none 1 N/A RI S NAME-PROXIMA-CENTAU 2 WFC3/UVI ACCUM UVIS G280 none none 19 none 1 N/A RI S NAME-PROXIMA-CENTAU 2 WFC3/UVI ACCUM UVIS G280 none none 20 none 1 N/A RI S NAME-PROXIMA-CENTAU 2 WFC3/UVI ACCUM UVIS G280 none none 21 none 1 N/A RI S NAME-PROXIMA-CENTAU 2 WFC3/UVI ACCUM UVIS G280 none none 22 none 1 N/A RI S NAME-PROXIMA-CENTAU 2 WFC3/UVI ACCUM UVIS G280 none none 23 none 1 N/A RI S NAME-PROXIMA-CENTAU 2 WFC3/UVI ACCUM UVIS G280 none none 24 none 1 N/A RI S NAME-PROXIMA-CENTAU 2 WFC3/UVI ACCUM UVIS G280 none none 25 none 1 N/A RI S 18140( 3) - 15-Dec-2025 13:48:25 - [ 91] Sub Exposures ------------------------------------------------------------------------------------------------------------------------------------ Target | Exp |Instr | Oper. | Aper |Spectral|Cent.|Primary |Secondary |Iteration |CR-SPLIT |Orbit |Duration Name | Num |Config | Mode | or FOV |Element |Wave.|Pattern Pos |Pattern Pos |Num |Num |Number | ------------------------------------------------------------------------------------------------------------------------------------ NAME-PROXIMA-CENTAU 2 WFC3/UVI ACCUM UVIS G280 none none 26 none 1 N/A RI S NAME-PROXIMA-CENTAU 2 WFC3/UVI ACCUM UVIS G280 none none 27 none 1 N/A RI S BIAS 3 WFC3/UVI ACCUM UVIS DEF none none 1 none 1 N/A S BIAS 3 WFC3/UVI ACCUM UVIS DEF none none 2 none 1 N/A S BIAS 3 WFC3/UVI ACCUM UVIS DEF none none 3 none 1 N/A S BIAS 3 WFC3/UVI ACCUM UVIS DEF none none 4 none 1 N/A S 18140( 3) - 15-Dec-2025 13:48:25 - [ 92] Visit: 23 Visit Requirements: ORIENT 0D TO 20 D; ORIENT 50D TO 120 D; ORIENT 180D TO 200 D; ORIENT 230D TO 300 D On Hold Comments: Additional Comments: The optional parameters SIZEAXIS1=2000 and SIZEAXIS2=300 are used for all exposures to minimize the data volume and hence time lost to buffer dumps. This is fine for the data that needs to be obtained because the spectum will occupy only a narrow swath of pixel rows within the field. This also requires the use of optional parameters CENTERAXIS1 and CENTERAXIS2 in order to "steer" the location of the subarray readout so that it is centered on the target spectrum. If we were positioning on chip 1 we could set CENTERAXIS2=TARGET. However, for the field center (nominal "UVIS" aperture) location on chip 2, we cannot center the subarray on the target because this would cause the subarray to extend into the chip gap, so we hardwire CENTERAXIS1=2136 and CENTERAXIS2=1216, which is intended to put the vertical center of the subarray on the zeroth order of the target spectrum. Chip 2 biases are taken at the end of the visit because the grism exposures use custom subarrays, which will not have matching biases from the WFC3 bias calibration program. For each visit we have phase constraints around the event of the planetary transit, both the orbital period of the planet and the phasing needed are placed on the target acq exposure. To avoid any contamination by several dim, nearby stars, we have placed Orient Ranges for the observations to reach our science goals. This results in ~15 transit opportunities for the UVIS observations in the coming months. Exposures ------------------------------------------------------------------------------------------------------------------------------------ Exp | Target | Instr | Oper. | Aper |Spectral|Central| Optional |Num| Time | Special Num | Name | Config | Mode | or FOV |Element |Waveln.| Parameters |Exp| (Total) | Requirements ------------------------------------------------------------------------------------------------------------------------------------ 1 NAME-PROXIM WFC3/UVI ACCUM G280-REF F300X FLASH=20, CENTERAXIS1=2136, 1 19 S (19 POS TARG null, -50; SEQ A-CENTAURI S CENTERAXIS2=1216, S) 1-3 NON-INT SIZEAXIS1=2000, SIZEAXIS2=300 Comments: For the reference image ("filter acq"), saturation in 259 seconds. 19.3 seconds gives SNR of 150. The nominal "UVIS" aperture is ~10" above the chip gap on chip 1; a Y-postarg of about -50" places the target near the center of subarray on chip 2, at an approximate XY position of (2048, 1024). CENTERAXIS1 and CENTERAXIS2 are used to center the subarray readout on the target spectrum, which will be displaced from the direct image of the target, in agreement with programs 16039, 16695, and 17082. We match the subarray size of the science exposures. We use FLASH=20 to meet the nominal count level. 18140( 3) - 15-Dec-2025 13:48:25 - [ 93] Exposures ------------------------------------------------------------------------------------------------------------------------------------ Exp | Target | Instr | Oper. | Aper |Spectral|Central| Optional |Num| Time | Special Num | Name | Config | Mode | or FOV |Element |Waveln.| Parameters |Exp| (Total) | Requirements ------------------------------------------------------------------------------------------------------------------------------------ ------------------------------------------------------------------------------------------------------------------------------------ 2 NAME-PROXIM WFC3/UVI ACCUM UVIS G280 FLASH=16, SIZEAXIS1=2000, 27 38 S (1026 POS TARG null, -50 A-CENTAURI S SIZEAXIS2=300, S) CENTERAXIS1=2136, CENTERAXIS2=1216 Comments: With exposure time of 40 second, we remain below 50% saturation (w/ saturation at 103 seconds) (with a maximum SNR of about 500 at about 7500 Angstrom), while remaining short enough for decent time-resolution of the flaring event. We also add a FLASH of 16, which when combined with the natural background of about 4 e- per exposure will result in >20 e- and better CTE. Nominal "UVIS" aperture is ~10" above the chip gap on chip 1; a Y-postarg of about -50" places the target near the center of subarray on chip 2. SIZEAXIS1=2000 and SIZEAXIS2=300 are used to minimize data volume, while CENTERAXIS1 and CENTERAXIS2 are used to center the subarray readout on the zeroth order of G280 spectrum. These parameters are based upon similar observations obtained successfully in GOs 13574 and 15288 but have been adjusted to better center the zeroth order spectrum on the sub-array (as done successfully for 16039). ------------------------------------------------------------------------------------------------------------------------------------ 3 BIAS WFC3/UVI ACCUM UVIS DEF SIZEAXIS1=2000, SIZEAXIS2=300, 4 0.0 S (0 S CENTERAXIS1=2136, S) CENTERAXIS2=1216 ------------------------------------------------------------------------------------------------------------------------------------ Sub Exposures ------------------------------------------------------------------------------------------------------------------------------------ Target | Exp |Instr | Oper. | Aper |Spectral|Cent.|Primary |Secondary |Iteration |CR-SPLIT |Orbit |Duration Name | Num |Config | Mode | or FOV |Element |Wave.|Pattern Pos |Pattern Pos |Num |Num |Number | ------------------------------------------------------------------------------------------------------------------------------------ NAME-PROXIMA-CENTAU 1 WFC3/UVI ACCUM G280-REF F300X none none none none 1 N/A RI S NAME-PROXIMA-CENTAU 2 WFC3/UVI ACCUM UVIS G280 none none 1 none 1 N/A RI S 18140( 3) - 15-Dec-2025 13:48:25 - [ 94] Sub Exposures ------------------------------------------------------------------------------------------------------------------------------------ Target | Exp |Instr | Oper. | Aper |Spectral|Cent.|Primary |Secondary |Iteration |CR-SPLIT |Orbit |Duration Name | Num |Config | Mode | or FOV |Element |Wave.|Pattern Pos |Pattern Pos |Num |Num |Number | ------------------------------------------------------------------------------------------------------------------------------------ NAME-PROXIMA-CENTAU 2 WFC3/UVI ACCUM UVIS G280 none none 2 none 1 N/A RI S NAME-PROXIMA-CENTAU 2 WFC3/UVI ACCUM UVIS G280 none none 3 none 1 N/A RI S NAME-PROXIMA-CENTAU 2 WFC3/UVI ACCUM UVIS G280 none none 4 none 1 N/A RI S NAME-PROXIMA-CENTAU 2 WFC3/UVI ACCUM UVIS G280 none none 5 none 1 N/A RI S NAME-PROXIMA-CENTAU 2 WFC3/UVI ACCUM UVIS G280 none none 6 none 1 N/A RI S NAME-PROXIMA-CENTAU 2 WFC3/UVI ACCUM UVIS G280 none none 7 none 1 N/A RI S NAME-PROXIMA-CENTAU 2 WFC3/UVI ACCUM UVIS G280 none none 8 none 1 N/A RI S NAME-PROXIMA-CENTAU 2 WFC3/UVI ACCUM UVIS G280 none none 9 none 1 N/A RI S NAME-PROXIMA-CENTAU 2 WFC3/UVI ACCUM UVIS G280 none none 10 none 1 N/A RI S NAME-PROXIMA-CENTAU 2 WFC3/UVI ACCUM UVIS G280 none none 11 none 1 N/A RI S NAME-PROXIMA-CENTAU 2 WFC3/UVI ACCUM UVIS G280 none none 12 none 1 N/A RI S NAME-PROXIMA-CENTAU 2 WFC3/UVI ACCUM UVIS G280 none none 13 none 1 N/A RI S NAME-PROXIMA-CENTAU 2 WFC3/UVI ACCUM UVIS G280 none none 14 none 1 N/A RI S NAME-PROXIMA-CENTAU 2 WFC3/UVI ACCUM UVIS G280 none none 15 none 1 N/A RI S NAME-PROXIMA-CENTAU 2 WFC3/UVI ACCUM UVIS G280 none none 16 none 1 N/A RI S NAME-PROXIMA-CENTAU 2 WFC3/UVI ACCUM UVIS G280 none none 17 none 1 N/A RI S NAME-PROXIMA-CENTAU 2 WFC3/UVI ACCUM UVIS G280 none none 18 none 1 N/A RI S NAME-PROXIMA-CENTAU 2 WFC3/UVI ACCUM UVIS G280 none none 19 none 1 N/A RI S NAME-PROXIMA-CENTAU 2 WFC3/UVI ACCUM UVIS G280 none none 20 none 1 N/A RI S NAME-PROXIMA-CENTAU 2 WFC3/UVI ACCUM UVIS G280 none none 21 none 1 N/A RI S NAME-PROXIMA-CENTAU 2 WFC3/UVI ACCUM UVIS G280 none none 22 none 1 N/A RI S NAME-PROXIMA-CENTAU 2 WFC3/UVI ACCUM UVIS G280 none none 23 none 1 N/A RI S NAME-PROXIMA-CENTAU 2 WFC3/UVI ACCUM UVIS G280 none none 24 none 1 N/A RI S NAME-PROXIMA-CENTAU 2 WFC3/UVI ACCUM UVIS G280 none none 25 none 1 N/A RI S 18140( 3) - 15-Dec-2025 13:48:25 - [ 95] Sub Exposures ------------------------------------------------------------------------------------------------------------------------------------ Target | Exp |Instr | Oper. | Aper |Spectral|Cent.|Primary |Secondary |Iteration |CR-SPLIT |Orbit |Duration Name | Num |Config | Mode | or FOV |Element |Wave.|Pattern Pos |Pattern Pos |Num |Num |Number | ------------------------------------------------------------------------------------------------------------------------------------ NAME-PROXIMA-CENTAU 2 WFC3/UVI ACCUM UVIS G280 none none 26 none 1 N/A RI S NAME-PROXIMA-CENTAU 2 WFC3/UVI ACCUM UVIS G280 none none 27 none 1 N/A RI S BIAS 3 WFC3/UVI ACCUM UVIS DEF none none 1 none 1 N/A S BIAS 3 WFC3/UVI ACCUM UVIS DEF none none 2 none 1 N/A S BIAS 3 WFC3/UVI ACCUM UVIS DEF none none 3 none 1 N/A S BIAS 3 WFC3/UVI ACCUM UVIS DEF none none 4 none 1 N/A S 18140( 3) - 15-Dec-2025 13:48:25 - [ 96] Summary Form for Proposal 18140 Item Used in this proposal ------------------------------------------------------------------------------------------------------------------------------------ Apertures G280-REF, UVIS ------------------------------------------------------------------------------------------------------------------------------------ Configurations WFC3/UVIS ------------------------------------------------------------------------------------------------------------------------------------ Opmodes ACCUM ------------------------------------------------------------------------------------------------------------------------------------ Optional Parameters CENTERAXIS1=2136, CENTERAXIS2=1216, FLASH=16, FLASH=20, SIZEAXIS1=2000, SIZEAXIS2=300 ------------------------------------------------------------------------------------------------------------------------------------ Special Requirements ORIENT 0D TO 20 D, ORIENT 180D TO 200 D, ORIENT 230D TO 300 D, ORIENT 50D TO 120 D, POS TARG null, -50, SEQ 1-3 NON-INT ------------------------------------------------------------------------------------------------------------------------------------ Spectral Elements DEF, F300X, G280 ------------------------------------------------------------------------------------------------------------------------------------ Target Names BIAS, NAME-PROXIMA-CENTAURI ------------------------------------------------------------------------------------------------------------------------------------