0 Assigned ID: 6901 ----- Attempting Submission 1 (Fri May 23 12:37:36 GMT 2025) ----- HST Phase I Proposal 6901 successfully submitted. Receipt: # 6901-1 ----- Attempting Submission 2 (Fri May 23 12:39:52 GMT 2025) ----- HST Phase I Proposal 6901 successfully submitted. Receipt: # 6901-2 0 ----- Attempting Submission 1 (Thu Jun 12 21:59:41 GMT 2025) ----- Accelerating Our Models of Stellar Flare Particles M-dwarf flares exhibit strong responses in the X-ray, ultraviolet (UV), and visible, and radio regimes, and these various emissions may affect the atmospheres and habitability of exoplanets. Our understanding of these energetic events is hampered by the limited amount of spectral and multi-wavelength observations than can be used to constrain their underlying energetics and extrapolations from solar models. We request for high-frequency radio data to probe the gyrosynchrotron radiation from flares in the optically thin part of the spectrum. This will allow us to constrain the initial electron beam energetics parameter space, which will be compared to current M-dwarf flaring models. For example, a recent HST NUV study has exemplified that extreme electron beams can reproduce NUV+optical M-dwarf flaring spectra using radiative-hydrodynamic models. However, this study lacked simultaneous radio data that probes the action of accelerated electrons needed to confirm these extreme estimates. We propose for a self-contained, comprehensive multi-wavelength dataset to follow-up on and expand these findings. This campaign will connect observational parameters to flaring models, explore justifications between wavelength extrapolations, and build pathways for modeling archival flares (depending on flaring degeneracies). This work will improve habitability estimates for M-dwarfs and provide flaring rates/models/priors for future campaigns. This goal of this project is to study M-dwarf flares with simultaneous high-frequency radio data, X-ray photometry/spectroscopy, and UV/optical spectroscopy. We choose YZ Cmi (M4.5Ve) as our target due to its high flaring rate from Kepler and TESS and lack of planets that may complicate light curve interpretation. YZ CMi is observable simultaneously by the VLA, HST, and XMM-Newton between October 02, 2025 and November 09, 2025, which sets our windows for HST visits. This program will use the WFC3/UVIS G280 grism of HST. Using the low-resolution spectra, we will be able to determine changes in the continuum emission between the quiescent emission and different flaring events. To this end, a exposure time of 45s is chosen to achieve a high SNR while still allowing for time-resolved spectral changes to be captured. A subarray setup is used based on Proposal 16039 (and previously 13574 and 15288) to minimize the data used and maximize on-source monitoring. We plan for a reference image with the F467M spectral element, which has a higher SNR for M-dwarf spectra than F300X and used in Proposal 16039. However, a reference image with the F300X filter is also taken as a backup, as it is recommended under Section 8.2 of the WFC3 Instrument Handbook. Four visits of three orbits are planned to occur simultaneously with the VLA observations, which will have 4 observing blocks of 5 hours each. Continuous orbits are necessary to monitor for flares and observe their full evolution when they occur, which can span from minutes to hours in the UV/optical bands. The high-frequency radio observations are very weather-dependent, thus HST observations are requested to be planned a few days in advance (Disruptive) based on the forecast at the VLA. PI Tristan is an expert in multi-wavelength M-dwarf flare phenomena with experience in TESS, VLA, and XMM-Newton data analysis and flare modeling. Co-I Osten is an expert on multi-wavelength observations of stellar flares including radio, optical, and X-ray analysis. Co-I Kowalski is an expert on radiative hydrodynamic modeling and interpretation of multi-wavelength aspects of both solar and stellar flares, with previous experience with both HST data analysis and subsequent flare modeling. Co-I Notsu is an expert in stellar flare observations with various experiences in multi-wavelength analysis, including NUV, X-ray, and optical data. Stellar Physics and Stellar Types 6 false false false false false false true SECONDARY NRAO VLA/25B-101 false AVAILABLE STAR M V-IV 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. G-285 GAIA-DR3-3136952686035250688 J2000 J2000 U=13.761 WFC3/UVIS Spectroscopic No No G280 WFC3/UVIS Imaging No No F300X The scheduling data was generated by CASM 33.1. CASM was run in Phase II mode. We set the field center location on chip 2 as recommended in the proposal guide on WFC3/UVIS G280. As in Proposal 16039, the optional parameters SIZEAXIS1=2250 and SIZEAXIS2=590 are used for all exposures to minimize data volume. This allows for parallel WFC3 Buffer Dumps in order to maximize on-source time. The spectrum of YZ CMi should be similar to LTT1445A from Proposal 16039, meaning it will only use a narrow swatch of pixel rows in the field and that these options are valid for the data output. The optional parameters CENTERAXIS1=2136 and CENTERAXIS2=1216 are then used to change the vertical center of the subarray on the zeroth order of the target spectrum. While centering on the target would be typical when positioning on chip 1, this would cause the subarray to extend into the chip gap when the field center location is on chip 2. Biases are taken at the end of each visit, as the exposures use custom subarrays. These will not have matching biases from the standard WFC3 bias calibration program. Observations should be simultaneous with VLA observations. (Tic-Visit :proposal-id 17943 :visit-id "01" :proposal-version -1 :trans-version "20250321" :date "12-Jun-2025 16:59:00.0" :trans-errors '(:WARNINGS 0 :ERRORS 0 :HEALTH-AND-SAFETY 0 :FATAL-ERRORS 0 :CONTINUABLE-FATALS 0) :number-of-orbits 3 :saa-model "29" :si-bright-earth-limb-angle 20.0 :data-volume 1476192 :tdrss-contact-duration 0 :coron NIL ) (Tic-Obset :proposal-id 17943 :visit-id "01" :obset-id "01" :pcs-mode "FGS" ) (Tic-Orbit :proposal-id 17943 :visit-id "01" :orbit-number 1 :pcs-time 380 :si-vis-utilization 2474 :al-overhead-at-end 69 :internal-dur-at-end 542 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 2913 :pcs-gap 0 ) (Tic-Orbit :proposal-id 17943 :visit-id "01" :orbit-number 2 :pcs-time 380 :si-vis-utilization 2508 :al-overhead-at-end 69 :internal-dur-at-end 542 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 2913 :pcs-gap 0 ) (Tic-Orbit :proposal-id 17943 :visit-id "01" :orbit-number 3 :pcs-time 380 :si-vis-utilization 2508 :al-overhead-at-end 69 :internal-dur-at-end 945 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 2913 :pcs-gap 0 ) true 3 0 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=2250 and SIZEAXIS2=590 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, with the adjustments from GO 16039 to better center the zeroth order spectrum on the sub-array. We use FLASH=20 for our CTE mitigation strategy during this observation. 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=2250 and SIZEAXIS2=590 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, with the adjustments from GO 16039 to better center the zeroth order spectrum on the sub-array. We use FLASH=20 is used based on ETC recommendations. 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=2250 and SIZEAXIS2=590 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, with the adjustments from GO 16039 to better center the zeroth order spectrum on the sub-array. Exposure times of 40 seconds have been chosen to obtain a high-SNR while keeping the time resolution at a level useful for determining changes over flaring events. The NUV wavelength of 3000 Angstrom is chosen in the ETC to best estimate the NUV quiescent expected.The optical range will be much stronger, and the NUV range of the spectrum will increase dramatically during events to levels similar or somewhat higher than the optical. No saturation is expected based on this exposure time. 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=2250 and SIZEAXIS2=590 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, with the adjustments from GO 16039 to better center the zeroth order spectrum on the sub-array. Exposure times of 40 seconds have been chosen to obtain a high-SNR while keeping the time resolution at a level useful for determining changes over flaring events. The NUV wavelength of 3000 Angstrom is chosen in the ETC to best estimate the NUV quiescent expected.The optical range will be much stronger, and the NUV range of the spectrum will increase dramatically during events to levels similar or somewhat higher than the optical. No saturation is expected based on this exposure time. 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=2250 and SIZEAXIS2=590 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, with the adjustments from GO 16039 to better center the zeroth order spectrum on the sub-array. Exposure times of 40 seconds have been chosen to obtain a high-SNR while keeping the time resolution at a level useful for determining changes over flaring events. The NUV wavelength of 3000 Angstrom is chosen in the ETC to best estimate the NUV quiescent expected.The optical range will be much stronger, and the NUV range of the spectrum will increase dramatically during events to levels similar or somewhat higher than the optical. No saturation is expected based on this exposure time. Bias frames based on previous, successful Proposals 11934 and 16039. These use the same sizeaxis and centeraxis as the observations for direct calibration. The scheduling data was generated by CASM 33.1. CASM was run in Phase II mode. We set the field center location on chip 2 as recommended in the proposal guide on WFC3/UVIS G280. As in Proposal 16039, the optional parameters SIZEAXIS1=2250 and SIZEAXIS2=590 are used for all exposures to minimize data volume. This allows for parallel WFC3 Buffer Dumps in order to maximize on-source time. The spectrum of YZ CMi should be similar to LTT1445A from Proposal 16039, meaning it will only use a narrow swatch of pixel rows in the field and that these options are valid for the data output. The optional parameters CENTERAXIS1=2136 and CENTERAXIS2=1216 are then used to change the vertical center of the subarray on the zeroth order of the target spectrum. While centering on the target would be typical when positioning on chip 1, this would cause the subarray to extend into the chip gap when the field center location is on chip 2. Biases are taken at the end of each visit, as the exposures use custom subarrays. These will not have matching biases from the standard WFC3 bias calibration program. Observations should be simultaneous with VLA observations. (Tic-Visit :proposal-id 17943 :visit-id "02" :proposal-version -1 :trans-version "20250321" :date "12-Jun-2025 16:59:01.0" :trans-errors '(:WARNINGS 0 :ERRORS 0 :HEALTH-AND-SAFETY 0 :FATAL-ERRORS 0 :CONTINUABLE-FATALS 0) :number-of-orbits 3 :saa-model "29" :si-bright-earth-limb-angle 20.0 :data-volume 1476192 :tdrss-contact-duration 0 :coron NIL ) (Tic-Obset :proposal-id 17943 :visit-id "02" :obset-id "02" :pcs-mode "FGS" ) (Tic-Orbit :proposal-id 17943 :visit-id "02" :orbit-number 1 :pcs-time 380 :si-vis-utilization 2474 :al-overhead-at-end 69 :internal-dur-at-end 542 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 2913 :pcs-gap 0 ) (Tic-Orbit :proposal-id 17943 :visit-id "02" :orbit-number 2 :pcs-time 380 :si-vis-utilization 2508 :al-overhead-at-end 69 :internal-dur-at-end 542 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 2913 :pcs-gap 0 ) (Tic-Orbit :proposal-id 17943 :visit-id "02" :orbit-number 3 :pcs-time 380 :si-vis-utilization 2508 :al-overhead-at-end 69 :internal-dur-at-end 945 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 2913 :pcs-gap 0 ) true 3 0 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=2250 and SIZEAXIS2=590 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, with the adjustments from GO 16039 to better center the zeroth order spectrum on the sub-array. We use FLASH=20 for our CTE mitigation strategy during this observation. 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=2250 and SIZEAXIS2=590 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, with the adjustments from GO 16039 to better center the zeroth order spectrum on the sub-array. We use FLASH=20 is used based on ETC recommendations. 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=2250 and SIZEAXIS2=590 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, with the adjustments from GO 16039 to better center the zeroth order spectrum on the sub-array. Exposure times of 40 seconds have been chosen to obtain a high-SNR while keeping the time resolution at a level useful for determining changes over flaring events. The NUV wavelength of 3000 Angstrom is chosen in the ETC to best estimate the NUV quiescent expected.The optical range will be much stronger, and the NUV range of the spectrum will increase dramatically during events to levels similar or somewhat higher than the optical. No saturation is expected based on this exposure time. 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=2250 and SIZEAXIS2=590 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, with the adjustments from GO 16039 to better center the zeroth order spectrum on the sub-array. Exposure times of 40 seconds have been chosen to obtain a high-SNR while keeping the time resolution at a level useful for determining changes over flaring events. The NUV wavelength of 3000 Angstrom is chosen in the ETC to best estimate the NUV quiescent expected.The optical range will be much stronger, and the NUV range of the spectrum will increase dramatically during events to levels similar or somewhat higher than the optical. No saturation is expected based on this exposure time. 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=2250 and SIZEAXIS2=590 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, with the adjustments from GO 16039 to better center the zeroth order spectrum on the sub-array. Exposure times of 40 seconds have been chosen to obtain a high-SNR while keeping the time resolution at a level useful for determining changes over flaring events. The NUV wavelength of 3000 Angstrom is chosen in the ETC to best estimate the NUV quiescent expected.The optical range will be much stronger, and the NUV range of the spectrum will increase dramatically during events to levels similar or somewhat higher than the optical. No saturation is expected based on this exposure time. Bias frames based on previous, successful Proposals 11934 and 16039. These use the same sizeaxis and centeraxis as the observations for direct calibration. The scheduling data was generated by CASM 33.1. CASM was run in Phase II mode. We set the field center location on chip 2 as recommended in the proposal guide on WFC3/UVIS G280. As in Proposal 16039, the optional parameters SIZEAXIS1=2250 and SIZEAXIS2=590 are used for all exposures to minimize data volume. This allows for parallel WFC3 Buffer Dumps in order to maximize on-source time. The spectrum of YZ CMi should be similar to LTT1445A from Proposal 16039, meaning it will only use a narrow swatch of pixel rows in the field and that these options are valid for the data output. The optional parameters CENTERAXIS1=2136 and CENTERAXIS2=1216 are then used to change the vertical center of the subarray on the zeroth order of the target spectrum. While centering on the target would be typical when positioning on chip 1, this would cause the subarray to extend into the chip gap when the field center location is on chip 2. Biases are taken at the end of each visit, as the exposures use custom subarrays. These will not have matching biases from the standard WFC3 bias calibration program. Observations should be simultaneous with VLA observations. (Tic-Visit :proposal-id 17943 :visit-id "03" :proposal-version -1 :trans-version "20250321" :date "12-Jun-2025 16:59:02.0" :trans-errors '(:WARNINGS 0 :ERRORS 0 :HEALTH-AND-SAFETY 0 :FATAL-ERRORS 0 :CONTINUABLE-FATALS 0) :number-of-orbits 3 :saa-model "29" :si-bright-earth-limb-angle 20.0 :data-volume 1476192 :tdrss-contact-duration 0 :coron NIL ) (Tic-Obset :proposal-id 17943 :visit-id "03" :obset-id "03" :pcs-mode "FGS" ) (Tic-Orbit :proposal-id 17943 :visit-id "03" :orbit-number 1 :pcs-time 380 :si-vis-utilization 2474 :al-overhead-at-end 69 :internal-dur-at-end 542 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 2913 :pcs-gap 0 ) (Tic-Orbit :proposal-id 17943 :visit-id "03" :orbit-number 2 :pcs-time 380 :si-vis-utilization 2508 :al-overhead-at-end 69 :internal-dur-at-end 542 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 2913 :pcs-gap 0 ) (Tic-Orbit :proposal-id 17943 :visit-id "03" :orbit-number 3 :pcs-time 380 :si-vis-utilization 2508 :al-overhead-at-end 69 :internal-dur-at-end 945 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 2913 :pcs-gap 0 ) true 3 0 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=2250 and SIZEAXIS2=590 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, with the adjustments from GO 16039 to better center the zeroth order spectrum on the sub-array. We use FLASH=20 for our CTE mitigation strategy during this observation. 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=2250 and SIZEAXIS2=590 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, with the adjustments from GO 16039 to better center the zeroth order spectrum on the sub-array. We use FLASH=20 is used based on ETC recommendations. 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=2250 and SIZEAXIS2=590 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, with the adjustments from GO 16039 to better center the zeroth order spectrum on the sub-array. Exposure times of 40 seconds have been chosen to obtain a high-SNR while keeping the time resolution at a level useful for determining changes over flaring events. The NUV wavelength of 3000 Angstrom is chosen in the ETC to best estimate the NUV quiescent expected.The optical range will be much stronger, and the NUV range of the spectrum will increase dramatically during events to levels similar or somewhat higher than the optical. No saturation is expected based on this exposure time. 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=2250 and SIZEAXIS2=590 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, with the adjustments from GO 16039 to better center the zeroth order spectrum on the sub-array. Exposure times of 40 seconds have been chosen to obtain a high-SNR while keeping the time resolution at a level useful for determining changes over flaring events. The NUV wavelength of 3000 Angstrom is chosen in the ETC to best estimate the NUV quiescent expected.The optical range will be much stronger, and the NUV range of the spectrum will increase dramatically during events to levels similar or somewhat higher than the optical. No saturation is expected based on this exposure time. 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=2250 and SIZEAXIS2=590 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, with the adjustments from GO 16039 to better center the zeroth order spectrum on the sub-array. Exposure times of 40 seconds have been chosen to obtain a high-SNR while keeping the time resolution at a level useful for determining changes over flaring events. The NUV wavelength of 3000 Angstrom is chosen in the ETC to best estimate the NUV quiescent expected.The optical range will be much stronger, and the NUV range of the spectrum will increase dramatically during events to levels similar or somewhat higher than the optical. No saturation is expected based on this exposure time. Bias frames based on previous, successful Proposals 11934 and 16039. These use the same sizeaxis and centeraxis as the observations for direct calibration. The scheduling data was generated by CASM 33.1. CASM was run in Phase II mode. We set the field center location on chip 2 as recommended in the proposal guide on WFC3/UVIS G280. As in Proposal 16039, the optional parameters SIZEAXIS1=2250 and SIZEAXIS2=590 are used for all exposures to minimize data volume. This allows for parallel WFC3 Buffer Dumps in order to maximize on-source time. The spectrum of YZ CMi should be similar to LTT1445A from Proposal 16039, meaning it will only use a narrow swatch of pixel rows in the field and that these options are valid for the data output. The optional parameters CENTERAXIS1=2136 and CENTERAXIS2=1216 are then used to change the vertical center of the subarray on the zeroth order of the target spectrum. While centering on the target would be typical when positioning on chip 1, this would cause the subarray to extend into the chip gap when the field center location is on chip 2. Biases are taken at the end of each visit, as the exposures use custom subarrays. These will not have matching biases from the standard WFC3 bias calibration program. Observations should be simultaneous with VLA observations. (Tic-Visit :proposal-id 17943 :visit-id "04" :proposal-version -1 :trans-version "20250321" :date "12-Jun-2025 16:59:03.0" :trans-errors '(:WARNINGS 0 :ERRORS 0 :HEALTH-AND-SAFETY 0 :FATAL-ERRORS 0 :CONTINUABLE-FATALS 0) :number-of-orbits 3 :saa-model "29" :si-bright-earth-limb-angle 20.0 :data-volume 1476192 :tdrss-contact-duration 0 :coron NIL ) (Tic-Obset :proposal-id 17943 :visit-id "04" :obset-id "04" :pcs-mode "FGS" ) (Tic-Orbit :proposal-id 17943 :visit-id "04" :orbit-number 1 :pcs-time 380 :si-vis-utilization 2474 :al-overhead-at-end 69 :internal-dur-at-end 542 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 2913 :pcs-gap 0 ) (Tic-Orbit :proposal-id 17943 :visit-id "04" :orbit-number 2 :pcs-time 380 :si-vis-utilization 2508 :al-overhead-at-end 69 :internal-dur-at-end 542 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 2913 :pcs-gap 0 ) (Tic-Orbit :proposal-id 17943 :visit-id "04" :orbit-number 3 :pcs-time 380 :si-vis-utilization 2508 :al-overhead-at-end 69 :internal-dur-at-end 945 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 2913 :pcs-gap 0 ) true 3 0 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=2250 and SIZEAXIS2=590 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, with the adjustments from GO 16039 to better center the zeroth order spectrum on the sub-array. We use FLASH=20 for our CTE mitigation strategy during this observation. 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=2250 and SIZEAXIS2=590 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, with the adjustments from GO 16039 to better center the zeroth order spectrum on the sub-array. We use FLASH=20 is used based on ETC recommendations. 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=2250 and SIZEAXIS2=590 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, with the adjustments from GO 16039 to better center the zeroth order spectrum on the sub-array. Exposure times of 40 seconds have been chosen to obtain a high-SNR while keeping the time resolution at a level useful for determining changes over flaring events. The NUV wavelength of 3000 Angstrom is chosen in the ETC to best estimate the NUV quiescent expected.The optical range will be much stronger, and the NUV range of the spectrum will increase dramatically during events to levels similar or somewhat higher than the optical. No saturation is expected based on this exposure time. 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=2250 and SIZEAXIS2=590 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, with the adjustments from GO 16039 to better center the zeroth order spectrum on the sub-array. Exposure times of 40 seconds have been chosen to obtain a high-SNR while keeping the time resolution at a level useful for determining changes over flaring events. The NUV wavelength of 3000 Angstrom is chosen in the ETC to best estimate the NUV quiescent expected.The optical range will be much stronger, and the NUV range of the spectrum will increase dramatically during events to levels similar or somewhat higher than the optical. No saturation is expected based on this exposure time. 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=2250 and SIZEAXIS2=590 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, with the adjustments from GO 16039 to better center the zeroth order spectrum on the sub-array. Exposure times of 40 seconds have been chosen to obtain a high-SNR while keeping the time resolution at a level useful for determining changes over flaring events. The NUV wavelength of 3000 Angstrom is chosen in the ETC to best estimate the NUV quiescent expected.The optical range will be much stronger, and the NUV range of the spectrum will increase dramatically during events to levels similar or somewhat higher than the optical. No saturation is expected based on this exposure time. Bias frames based on previous, successful Proposals 11934 and 16039. These use the same sizeaxis and centeraxis as the observations for direct calibration.