16189( 14) - 09-May-2023 14:31:55 - [ 1] HUBBLE SPACE TELESCOPE OBSERVING PROGRAM 16189 Version: 14 Check-in Time: 09-May-2023 14:31:55 STScI Edit Number: 5 Title UV Spectroscopic Signatures from Type Ia Supernovae Strongly Interacting with a Circumstellar Medium ------------------------------------------------------------------------------------ Type Cycle GO 28 ------------------------------------------------------------------------------------ Investigators Contact? PI: Dr. Ori Dosovitz Fox Space Telescope Science Institute Y CoI: Ms. K. Azalee Bostroem University of California - Davis N CoI: Prof. Alex V. Filippenko University of California - Berkeley N CoI: Prof. Ryan Foley University of California - Santa Cruz N CoI: Dr. Melissa Lynn Graham University of Washington N CoI: Dr. Patrick Kelly University of Minnesota - Twin Cities N CoI: Dr. Jon Mauerhan The Aerospace Corporation N CoI: Dr. Francesco Taddia Stockholm University N ------------------------------------------------------------------------------------ Abstract Type Ia supernovae (SNe Ia) are well known for their use as precise cosmological distance indicators due to a standardizable peak luminosity resulting from a thermonuclear explosion. A growing subset of SNe Ia, however, show evidence for interaction with a dense circumstellar medium during the first year post-explosion, and sometimes longer (SNe Ia-CSM). The origin of this dense CSM is unknown and suggests either (a) the less typical single-degenerate progenitor scenario must be considered, or (b) the exploding star was not a thermonuclear explosion of a white dwarf at all (i.e., core collapse). The ultraviolet (UV) offers a unique opportunity to determine the true nature of the SNe Ia-CSM subclass. Unlike optical wavelengths, which can sometimes yield ambiguous classifications, the UV has distinguishing features due to its sensitivity to the composition of the optically thin ejecta that are illuminated by X-rays generated by shock interaction. Yet not a single UV spectrum exists for this subclass. Here we propose a non-disruptive ToO with HST/STIS to obtain 3 epochs (5 orbits each) of UV spectra of a SN Ia-CSM within 100 Mpc. This program will not only distinguish between the SN explosion mechanisms, but also trace CSM interaction, constrain the progenitor mass loss history, and identify late-time heating mechanisms of warm dust. Coinciding with Cycle 28's UV Initiative, this program offers new insights regarding both the progenitor and explosion characteristics of the SN Ia-CSM subclass. ------------------------------------------------------------------------------------ Observations Description ------------------------ We propose to obtain 3 epochs (5 orbits each) of STIS-MAMA spectra of a single Type Ia-CSM supernova (SN Ia-CSM) within ~150 Mpc. The goal is to detect UV signatures that can distinguish between core-collapse and thermonuclear progenitor scenarios. These observations will also trace circumstellar interaction, constrain the progenitor mass loss, and identify late-time heating mechanisms for potential warm dust. The initial spectrum will be triggered as a non-disruptive ToO, *although observations should be scheduled as soon as possible*. Earlier observations 16189( 14) - 09-May-2023 14:31:55 - [ 2] will be more sensitive to the key UV iron-group features of thermnuclear explosions. As the SN evolves, reprocessed X-rays from shock interaction will illuminate the ejecta, reaching deeper layers as the ejecta expand. The second epoch should therefore be obtained ~2 months following the first epoch. The third epoch should be scheduled ~9 months after the first epoch. Each epoch will include observations in both the G140 and G230L bandpasses. We choose STIS over COS for several reasons. Most importantly, STIS offers spatially resolved spectra that exploit the intrinsically high resolution of HST over a large spectral range (accommodating both the C III] 1909 Ang and Mg II 2800 Ang lines). The long slit length will allow us to subtract contamination from zodiacal light, earthshine, the host galaxy, and H II regions. STIS also has superior sensitivity to COS in the NUV. While COS is optimized for isolated, faint point sources in the FUV with medium resolution, we would suffer from less wavelength coverage and require more integrations. We would also lose the advantages of the slit described above. *Impact of Gyros* This is a ToO. We have considered the impact of reduced gyro operations on our program. We will start with the assumption that gyro operations will be normal; our durations in this case should be 5, 5, and 5 orbits for Visits 1, 2, and 3 (respectively). Each visit requires 5 orbits because all exposures must be obtained at the same time given the rapid evolution of the SN light-curve. If the trigger occurs, or visits are scheduled, following the loss of a gyro and shorter visits are necessary, we will likely be able to restructure our visits with 3 FUV exposues and 2 NUV exposures. However, given the time sensitivity of the obsevations (the FUV and NUV must be taken at similar epochs), the first two visits cannot be separated by more than a few days. ------------------------------------------------------------------------------------ 16189( 14) - 09-May-2023 14:31:55 - [ 3] TARGET LIST Fixed Targets ------------------------------------------------------------------------------------------------------------------------------------ Tar| Target | Target | Target |Coord | Radial | Flux data No | Name | Description | Position |Eqnx | Vel. | ------------------------------------------------------------------------------------------------------------------------------------ 2 ZTF21AAABWZX EXT-STAR, SUPERNOVA, RA-OFF=-0.535S, J2000 V = 18 SUPERNOVA TYPE IA DEC-OFF=-12.449", FROM 3 Extended: NO ------------------------------------------------------------------------------------------------------------------------------------ 3 OFFSETSTAR EXT-STAR, F0-F2 RA=15H43M11.9219S, J2000 V = 16 DEC=+17D48'59.61" Reference Frame: ICRS Extended: NO Comments: http://vizier.u-strasbg.fr/viz-bin/VizieR-5?-info=XML&-out. add=.&-source=I/352/gedr3dis&-c=235.79967456886%2B17.816557 60935&-c.rs=0.5 -3.155767575385198 mas/yr RA -5.888742957243794 mas/yr DEC ------------------------------------------------------------------------------------------------------------------------------------ 16189( 14) - 09-May-2023 14:31:55 - [ 4] TARGET LIST Generic Targets ------------------------------------------------------------------------------------------------------------------------------------ Tar| Target | Target | Selection Criteria | Flux data No | Name | Description | | ------------------------------------------------------------------------------------------------------------------------------------ 1 SN1 TYPE IA-CSM WITHIN 150 MPC V = 15 Comments: Expected maximum local count rate of 10.4 counts/s/pixel (at 2900 Ang) and a global rate of 6200 counts/s, both of which are significantly below the STIS/MAMA limits given in Table 7.8 of the STIS Handbook. We find that we will be safe for an event like SN 1998S to within 7 Mpc, which we don't anticipate being a problem. Such a nearby and bright SN Ia-CSM should occur once every few decades, and in this rare (and exciting!) case, we would request a change to STIS/CCD+G230L. ------------------------------------------------------------------------------------------------------------------------------------ 16189( 14) - 09-May-2023 14:31:55 - [ 5] Visit: 01 (STIS-SN1) Visit Requirements: ON HOLD ; TOO RESPONSE TIME 21.0D On Hold Comments: Target-of-Opportunity. The initial spectrum will be triggered as a non-disruptive ToO, *although observations should be scheduled as soon as possible*. Additional Comments: Likely to acquire on bright SN. 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 OFFSETSTAR STIS/CCD ACQ F28X50LP MIRROR 1 3 S (3 S) Comments: Used sn2008j-20080216.205-ui.flm (day 32 spectrum) normalized to V=16. SN should be bright during initial acquisition. Latest ETC calculation here: STIS.ta.1518260 ------------------------------------------------------------------------------------------------------------------------------------ 16189( 14) - 09-May-2023 14:31:55 - [ 6] 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 ZTF21AAABWZ STIS/FUV TIME-TA 52X0.5D1 G140L 1425 BUFFER-TIME=3644 1 2500 S X -MAMA G see below (2184 S) Comments: Assuming 98S-like spectrum on day 14 (sn1998s-19980316.000-hst.fits). The FUV/G140L is plagued by varying geo-coronal emission as HST orbits. The downside to this is that the varying Ly/alpha could affect the nearby Oxygen (1300 Ang), which would be a very useful discriminator in the case of a core-collapse event (see original proposal). To monitor the geo-coronal emission at a resolution < 1 orbit, the contact scientist recommended that we utilize the time-tag exposures with a buffer readout time of t_orbit/2 = 3000/2 = 1500. So if you set the buffer time for G140L time-tag to 300 s, that would accommodate global rates of up to about 6600 c/s while keeping the total number of buffer dumps near the limit of 30 dumps/visit that we prefer to keep to. Perhaps that represents a reasonable compromise between doing an excessive number of buffer dumps and still covering yourself at higher count rates? In the unlikely event the target came out brighter than this, you'd probably have to modify the G230L observation anyway so you could change the G140L back to ACCUM mode at the same time. The main down side of TIME-TAG vs ACCUM is that with TIME-TAG you're effectively limited to global rates (source + detector background) of under about 20, 000 c/s, and you need to set a reasonable upper limit to the expected count rate to be able to estimate the needed buffer time. So for a very bright target, you might have to switch back to ACCUM observations. See section 11.1.3 of the STIS IHB for additional details about TIME-TAG mode. ------------------------------------------------------------------------------------------------------------------------------------ 16189( 14) - 09-May-2023 14:31:55 - [ 7] Exposures ------------------------------------------------------------------------------------------------------------------------------------ Exp | Target | Instr | Oper. | Aper |Spectral|Central| Optional |Num| Time | Special Num | Name | Config | Mode | or FOV |Element |Waveln.| Parameters |Exp| (Total) | Requirements ------------------------------------------------------------------------------------------------------------------------------------ 3 ZTF21AAABWZ STIS/FUV TIME-TA 52X0.5D1 G140L 1425 BUFFER-TIME=3644 1 2500 S X -MAMA G see below (2736 S) Comments: Assuming 98S-like spectrum on day 14 (sn1998s-19980316.000-hst.fits). ------------------------------------------------------------------------------------------------------------------------------------ 4 ZTF21AAABWZ STIS/FUV TIME-TA 52X0.5D1 G140L 1425 BUFFER-TIME=3644 1 2500 S X -MAMA G see below (2694 S) Comments: Assuming 98S-like spectrum on day 14 (sn1998s-19980316.000-hst.fits). ------------------------------------------------------------------------------------------------------------------------------------ 5 ZTF21AAABWZ STIS/NUV TIME-TA 52X0.5 G230L 2376 BUFFER-TIME=686 1 2500 S X -MAMA G see below (2713 S) ------------------------------------------------------------------------------------------------------------------------------------ 6 ZTF21AAABWZ STIS/NUV TIME-TA 52X0.5 G230L 2376 BUFFER-TIME=686 1 2500 S X -MAMA G see below (2713 S) ------------------------------------------------------------------------------------------------------------------------------------ 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 | ------------------------------------------------------------------------------------------------------------------------------------ OFFSETSTAR 1 STIS/CCD ACQ F28X50LP MIRROR none none none none 1 N/A ZTF21AAABWZX 2 STIS/FUV TIME-TA 52X0.5D1 G140L 1425 none none none none 1 2184.0 S -MAMA G ZTF21AAABWZX 3 STIS/FUV TIME-TA 52X0.5D1 G140L 1425 none none none none 2 2736.0 S -MAMA G ZTF21AAABWZX 4 STIS/FUV TIME-TA 52X0.5D1 G140L 1425 none none none none 3 2694.0 S -MAMA G ZTF21AAABWZX 5 STIS/NUV TIME-TA 52X0.5 G230L 2376 none none none none 4 2713.0 S -MAMA G ZTF21AAABWZX 6 STIS/NUV TIME-TA 52X0.5 G230L 2376 none none none none 5 2713.0 S -MAMA G 16189( 14) - 09-May-2023 14:31:55 - [ 8] Visit: 02 (STIS-SN1) Visit Requirements: AFTER Z1 BY 50 D TO 80 D; ON HOLD ; TOO RESPONSE TIME 21.0D On Hold Comments: Target-of-Opportunity. The initial spectrum will be triggered as a non-disruptive ToO, *although observations should be scheduled as soon as possible*. Additional Comments: Likely to acquire on bright SN. 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 OFFSETSTAR STIS/CCD ACQ F28X50LP MIRROR 1 3 S (3 S) Comments: Used sn2008j-20080216.205-ui.flm (day 32 spectrum) normalized to V=16. SN should be bright during initial acquisition. ------------------------------------------------------------------------------------------------------------------------------------ 2 ZTF21AAABWZ STIS/FUV TIME-TA 52X0.5D1 G140L 1425 BUFFER-TIME=3644 1 2500 S X -MAMA G see below (2184 S) Comments: Assuming 98S-like spectrum on day 14 (sn1998s-19980316.000-hst.fits). ------------------------------------------------------------------------------------------------------------------------------------ 3 ZTF21AAABWZ STIS/FUV TIME-TA 52X0.5D1 G140L 1425 BUFFER-TIME=3644 1 2500 S X -MAMA G see below (2736 S) Comments: Assuming 98S-like spectrum on day 14 (sn1998s-19980316.000-hst.fits). ------------------------------------------------------------------------------------------------------------------------------------ 4 ZTF21AAABWZ STIS/FUV TIME-TA 52X0.5D1 G140L 1425 BUFFER-TIME=3644 1 2500 S X -MAMA G see below (2694 S) Comments: Assuming 98S-like spectrum on day 14 (sn1998s-19980316.000-hst.fits). ------------------------------------------------------------------------------------------------------------------------------------ 5 OFFSETSTAR STIS/CCD ACQ F28X50LP MIRROR 1 3 S (3 S) Comments: Used sn2008j-20080216.205-ui.flm (day 32 spectrum) normalized to V=16. SN should be bright during initial acquisition. ------------------------------------------------------------------------------------------------------------------------------------ 6 ZTF21AAABWZ STIS/NUV TIME-TA 52X0.5 G230L 2376 BUFFER-TIME=686 1 750 S X -MAMA G see below (2017 S) ------------------------------------------------------------------------------------------------------------------------------------ 7 ZTF21AAABWZ STIS/NUV TIME-TA 52X0.5 G230L 2376 BUFFER-TIME=686 1 750 S X -MAMA G see below (2713 S) ------------------------------------------------------------------------------------------------------------------------------------ 16189( 14) - 09-May-2023 14:31:55 - [ 9] 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 | ------------------------------------------------------------------------------------------------------------------------------------ OFFSETSTAR 1 STIS/CCD ACQ F28X50LP MIRROR none none none none 1 N/A ZTF21AAABWZX 2 STIS/FUV TIME-TA 52X0.5D1 G140L 1425 none none none none 1 2184.0 S -MAMA G ZTF21AAABWZX 3 STIS/FUV TIME-TA 52X0.5D1 G140L 1425 none none none none 2 2736.0 S -MAMA G ZTF21AAABWZX 4 STIS/FUV TIME-TA 52X0.5D1 G140L 1425 none none none none 3 2694.0 S -MAMA G OFFSETSTAR 5 STIS/CCD ACQ F28X50LP MIRROR none none none none 4 N/A ZTF21AAABWZX 6 STIS/NUV TIME-TA 52X0.5 G230L 2376 none none none none 4 2017 S -MAMA G ZTF21AAABWZX 7 STIS/NUV TIME-TA 52X0.5 G230L 2376 none none none none 5 2713.0 S -MAMA G 16189( 14) - 09-May-2023 14:31:55 - [ 10] Visit: 03 (STIS-SN1) Visit Requirements: AFTER 02 BY 200 D TO 240 D; ON HOLD ; TOO RESPONSE TIME 21.0D On Hold Comments: Target-of-Opportunity. The initial spectrum will be triggered as a non-disruptive ToO, *although observations should be scheduled as soon as possible*. Additional Comments: Likely to acquire on bright SN. 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 OFFSETSTAR STIS/CCD ACQ F28X50LP MIRROR 1 3 S (3 S) Comments: Used sn2008j-20080216.205-ui.flm (day 32 spectrum) normalized to V=16. SN should be bright during initial acquisition. ------------------------------------------------------------------------------------------------------------------------------------ 2 ZTF21AAABWZ STIS/FUV TIME-TA 52X0.5D1 G140L 1425 BUFFER-TIME=3644 1 2500 S X -MAMA G see below (2184 S) Comments: Assuming 98S-like spectrum on day 14 (sn1998s-19980316.000-hst.fits). ------------------------------------------------------------------------------------------------------------------------------------ 3 ZTF21AAABWZ STIS/FUV TIME-TA 52X0.5D1 G140L 1425 BUFFER-TIME=3644 1 2500 S X -MAMA G see below (2736 S) Comments: Assuming 98S-like spectrum on day 14 (sn1998s-19980316.000-hst.fits). ------------------------------------------------------------------------------------------------------------------------------------ 4 ZTF21AAABWZ STIS/FUV TIME-TA 52X0.5D1 G140L 1425 BUFFER-TIME=3644 1 2500 S X -MAMA G see below (2694 S) Comments: Assuming 98S-like spectrum on day 14 (sn1998s-19980316.000-hst.fits). ------------------------------------------------------------------------------------------------------------------------------------ 5 ZTF21AAABWZ STIS/NUV TIME-TA 52X0.5 G230L 2376 BUFFER-TIME=686 1 750 S X -MAMA G see below (2713 S) ------------------------------------------------------------------------------------------------------------------------------------ 6 ZTF21AAABWZ STIS/NUV TIME-TA 52X0.5 G230L 2376 BUFFER-TIME=686 1 750 S X -MAMA G see below (2713 S) ------------------------------------------------------------------------------------------------------------------------------------ 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 | ------------------------------------------------------------------------------------------------------------------------------------ OFFSETSTAR 1 STIS/CCD ACQ F28X50LP MIRROR none none none none 1 N/A 16189( 14) - 09-May-2023 14:31:55 - [ 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 | ------------------------------------------------------------------------------------------------------------------------------------ ZTF21AAABWZX 2 STIS/FUV TIME-TA 52X0.5D1 G140L 1425 none none none none 1 2184.0 S -MAMA G ZTF21AAABWZX 3 STIS/FUV TIME-TA 52X0.5D1 G140L 1425 none none none none 2 2736.0 S -MAMA G ZTF21AAABWZX 4 STIS/FUV TIME-TA 52X0.5D1 G140L 1425 none none none none 3 2694.0 S -MAMA G ZTF21AAABWZX 5 STIS/NUV TIME-TA 52X0.5 G230L 2376 none none none none 4 2713.0 S -MAMA G ZTF21AAABWZX 6 STIS/NUV TIME-TA 52X0.5 G230L 2376 none none none none 5 2713.0 S -MAMA G 16189( 14) - 09-May-2023 14:31:55 - [ 12] Visit: Z1 (STIS-SN1_HOPR01) Visit Requirements: ON HOLD ; TOO RESPONSE TIME 21.0D On Hold Comments: Target-of-Opportunity. The initial spectrum will be triggered as a non-disruptive ToO, *although observations should be scheduled as soon as possible*. Additional Comments: Likely to acquire on bright SN. 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 OFFSETSTAR STIS/CCD ACQ F28X50LP MIRROR 1 3 S (3 S) Comments: Used sn2008j-20080216.205-ui.flm (day 32 spectrum) normalized to V=16. SN should be bright during initial acquisition. Latest ETC calculation here: STIS.ta.1518260 ------------------------------------------------------------------------------------------------------------------------------------ 16189( 14) - 09-May-2023 14:31:55 - [ 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 ZTF21AAABWZ STIS/FUV TIME-TA 52X0.5D1 G140L 1425 BUFFER-TIME=3644 1 2500 S X -MAMA G see below (2184 S) Comments: Assuming 98S-like spectrum on day 14 (sn1998s-19980316.000-hst.fits). The FUV/G140L is plagued by varying geo-coronal emission as HST orbits. The downside to this is that the varying Ly/alpha could affect the nearby Oxygen (1300 Ang), which would be a very useful discriminator in the case of a core-collapse event (see original proposal). To monitor the geo-coronal emission at a resolution < 1 orbit, the contact scientist recommended that we utilize the time-tag exposures with a buffer readout time of t_orbit/2 = 3000/2 = 1500. So if you set the buffer time for G140L time-tag to 300 s, that would accommodate global rates of up to about 6600 c/s while keeping the total number of buffer dumps near the limit of 30 dumps/visit that we prefer to keep to. Perhaps that represents a reasonable compromise between doing an excessive number of buffer dumps and still covering yourself at higher count rates? In the unlikely event the target came out brighter than this, you'd probably have to modify the G230L observation anyway so you could change the G140L back to ACCUM mode at the same time. The main down side of TIME-TAG vs ACCUM is that with TIME-TAG you're effectively limited to global rates (source + detector background) of under about 20, 000 c/s, and you need to set a reasonable upper limit to the expected count rate to be able to estimate the needed buffer time. So for a very bright target, you might have to switch back to ACCUM observations. See section 11.1.3 of the STIS IHB for additional details about TIME-TAG mode. ------------------------------------------------------------------------------------------------------------------------------------ 16189( 14) - 09-May-2023 14:31:55 - [ 14] Exposures ------------------------------------------------------------------------------------------------------------------------------------ Exp | Target | Instr | Oper. | Aper |Spectral|Central| Optional |Num| Time | Special Num | Name | Config | Mode | or FOV |Element |Waveln.| Parameters |Exp| (Total) | Requirements ------------------------------------------------------------------------------------------------------------------------------------ 3 ZTF21AAABWZ STIS/FUV TIME-TA 52X0.5D1 G140L 1425 BUFFER-TIME=3644 1 2500 S X -MAMA G see below (2736 S) Comments: Assuming 98S-like spectrum on day 14 (sn1998s-19980316.000-hst.fits). ------------------------------------------------------------------------------------------------------------------------------------ 4 ZTF21AAABWZ STIS/FUV TIME-TA 52X0.5D1 G140L 1425 BUFFER-TIME=3644 1 2500 S X -MAMA G see below (2694 S) Comments: Assuming 98S-like spectrum on day 14 (sn1998s-19980316.000-hst.fits). ------------------------------------------------------------------------------------------------------------------------------------ 5 ZTF21AAABWZ STIS/NUV TIME-TA 52X0.5 G230L 2376 BUFFER-TIME=686 1 2500 S X -MAMA G see below (2713 S) ------------------------------------------------------------------------------------------------------------------------------------ 6 ZTF21AAABWZ STIS/NUV TIME-TA 52X0.5 G230L 2376 BUFFER-TIME=686 1 2500 S X -MAMA G see below (2713 S) ------------------------------------------------------------------------------------------------------------------------------------ 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 | ------------------------------------------------------------------------------------------------------------------------------------ OFFSETSTAR 1 STIS/CCD ACQ F28X50LP MIRROR none none none none 1 N/A ZTF21AAABWZX 2 STIS/FUV TIME-TA 52X0.5D1 G140L 1425 none none none none 1 2184.0 S -MAMA G ZTF21AAABWZX 3 STIS/FUV TIME-TA 52X0.5D1 G140L 1425 none none none none 2 2736.0 S -MAMA G ZTF21AAABWZX 4 STIS/FUV TIME-TA 52X0.5D1 G140L 1425 none none none none 3 2694.0 S -MAMA G ZTF21AAABWZX 5 STIS/NUV TIME-TA 52X0.5 G230L 2376 none none none none 4 2713.0 S -MAMA G ZTF21AAABWZX 6 STIS/NUV TIME-TA 52X0.5 G230L 2376 none none none none 5 2713.0 S -MAMA G 16189( 14) - 09-May-2023 14:31:55 - [ 15] Visit: Z2 (STIS-SN1_HOPR) Visit Requirements: ON HOLD ; TOO RESPONSE TIME 21.0D On Hold Comments: Target-of-Opportunity. The initial spectrum will be triggered as a non-disruptive ToO, *although observations should be scheduled as soon as possible*. Additional Comments: Likely to acquire on bright SN. 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 OFFSETSTAR STIS/CCD ACQ F28X50LP MIRROR 1 3 S (3 S) Comments: Used sn2008j-20080216.205-ui.flm (day 32 spectrum) normalized to V=16. SN should be bright during initial acquisition. Latest ETC calculation here: STIS.ta.1518260 ------------------------------------------------------------------------------------------------------------------------------------ 16189( 14) - 09-May-2023 14:31:55 - [ 16] 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 ZTF21AAABWZ STIS/FUV TIME-TA 52X0.5D1 G140L 1425 BUFFER-TIME=3644 1 2500 S X -MAMA G see below (2184 S) Comments: Assuming 98S-like spectrum on day 14 (sn1998s-19980316.000-hst.fits). The FUV/G140L is plagued by varying geo-coronal emission as HST orbits. The downside to this is that the varying Ly/alpha could affect the nearby Oxygen (1300 Ang), which would be a very useful discriminator in the case of a core-collapse event (see original proposal). To monitor the geo-coronal emission at a resolution < 1 orbit, the contact scientist recommended that we utilize the time-tag exposures with a buffer readout time of t_orbit/2 = 3000/2 = 1500. So if you set the buffer time for G140L time-tag to 300 s, that would accommodate global rates of up to about 6600 c/s while keeping the total number of buffer dumps near the limit of 30 dumps/visit that we prefer to keep to. Perhaps that represents a reasonable compromise between doing an excessive number of buffer dumps and still covering yourself at higher count rates? In the unlikely event the target came out brighter than this, you'd probably have to modify the G230L observation anyway so you could change the G140L back to ACCUM mode at the same time. The main down side of TIME-TAG vs ACCUM is that with TIME-TAG you're effectively limited to global rates (source + detector background) of under about 20, 000 c/s, and you need to set a reasonable upper limit to the expected count rate to be able to estimate the needed buffer time. So for a very bright target, you might have to switch back to ACCUM observations. See section 11.1.3 of the STIS IHB for additional details about TIME-TAG mode. ------------------------------------------------------------------------------------------------------------------------------------ 16189( 14) - 09-May-2023 14:31:55 - [ 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 ------------------------------------------------------------------------------------------------------------------------------------ 3 ZTF21AAABWZ STIS/FUV TIME-TA 52X0.5D1 G140L 1425 BUFFER-TIME=3644 1 2500 S X -MAMA G see below (2736 S) Comments: Assuming 98S-like spectrum on day 14 (sn1998s-19980316.000-hst.fits). ------------------------------------------------------------------------------------------------------------------------------------ 4 ZTF21AAABWZ STIS/FUV TIME-TA 52X0.5D1 G140L 1425 BUFFER-TIME=3644 1 2500 S X -MAMA G see below (2694 S) Comments: Assuming 98S-like spectrum on day 14 (sn1998s-19980316.000-hst.fits). ------------------------------------------------------------------------------------------------------------------------------------ 5 ZTF21AAABWZ STIS/NUV TIME-TA 52X0.5 G230L 2376 BUFFER-TIME=686 1 2500 S X -MAMA G see below (2713 S) ------------------------------------------------------------------------------------------------------------------------------------ 6 ZTF21AAABWZ STIS/NUV TIME-TA 52X0.5 G230L 2376 BUFFER-TIME=686 1 2500 S X -MAMA G see below (2713 S) ------------------------------------------------------------------------------------------------------------------------------------ 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 | ------------------------------------------------------------------------------------------------------------------------------------ OFFSETSTAR 1 STIS/CCD ACQ F28X50LP MIRROR none none none none 1 N/A ZTF21AAABWZX 2 STIS/FUV TIME-TA 52X0.5D1 G140L 1425 none none none none 1 2184.0 S -MAMA G ZTF21AAABWZX 3 STIS/FUV TIME-TA 52X0.5D1 G140L 1425 none none none none 2 2736.0 S -MAMA G ZTF21AAABWZX 4 STIS/FUV TIME-TA 52X0.5D1 G140L 1425 none none none none 3 2694.0 S -MAMA G ZTF21AAABWZX 5 STIS/NUV TIME-TA 52X0.5 G230L 2376 none none none none 4 2713.0 S -MAMA G ZTF21AAABWZX 6 STIS/NUV TIME-TA 52X0.5 G230L 2376 none none none none 5 2713.0 S -MAMA G 16189( 14) - 09-May-2023 14:31:55 - [ 18] Visit: Z3 (STIS-SN1_HOPR) Visit Requirements: ON HOLD ; TOO RESPONSE TIME 21.0D On Hold Comments: Target-of-Opportunity. The initial spectrum will be triggered as a non-disruptive ToO, *although observations should be scheduled as soon as possible*. Additional Comments: Likely to acquire on bright SN. 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 OFFSETSTAR STIS/CCD ACQ F28X50LP MIRROR 1 10 S (10 S) Comments: Used sn2008j-20080216.205-ui.flm (day 32 spectrum) normalized to V=16. SN should be bright during initial acquisition. Latest ETC calculation here: STIS.ta.1518260 ------------------------------------------------------------------------------------------------------------------------------------ 16189( 14) - 09-May-2023 14:31:55 - [ 19] 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 ZTF21AAABWZ STIS/FUV TIME-TA 52X0.5D1 G140L 1425 BUFFER-TIME=3644 1 2500 S X -MAMA G see below (2156 S) Comments: Assuming 98S-like spectrum on day 14 (sn1998s-19980316.000-hst.fits). The FUV/G140L is plagued by varying geo-coronal emission as HST orbits. The downside to this is that the varying Ly/alpha could affect the nearby Oxygen (1300 Ang), which would be a very useful discriminator in the case of a core-collapse event (see original proposal). To monitor the geo-coronal emission at a resolution < 1 orbit, the contact scientist recommended that we utilize the time-tag exposures with a buffer readout time of t_orbit/2 = 3000/2 = 1500. So if you set the buffer time for G140L time-tag to 300 s, that would accommodate global rates of up to about 6600 c/s while keeping the total number of buffer dumps near the limit of 30 dumps/visit that we prefer to keep to. Perhaps that represents a reasonable compromise between doing an excessive number of buffer dumps and still covering yourself at higher count rates? In the unlikely event the target came out brighter than this, you'd probably have to modify the G230L observation anyway so you could change the G140L back to ACCUM mode at the same time. The main down side of TIME-TAG vs ACCUM is that with TIME-TAG you're effectively limited to global rates (source + detector background) of under about 20, 000 c/s, and you need to set a reasonable upper limit to the expected count rate to be able to estimate the needed buffer time. So for a very bright target, you might have to switch back to ACCUM observations. See section 11.1.3 of the STIS IHB for additional details about TIME-TAG mode. ------------------------------------------------------------------------------------------------------------------------------------ 16189( 14) - 09-May-2023 14:31:55 - [ 20] Exposures ------------------------------------------------------------------------------------------------------------------------------------ Exp | Target | Instr | Oper. | Aper |Spectral|Central| Optional |Num| Time | Special Num | Name | Config | Mode | or FOV |Element |Waveln.| Parameters |Exp| (Total) | Requirements ------------------------------------------------------------------------------------------------------------------------------------ 3 ZTF21AAABWZ STIS/FUV TIME-TA 52X0.5D1 G140L 1425 BUFFER-TIME=3644 1 2500 S X -MAMA G see below (2736 S) Comments: Assuming 98S-like spectrum on day 14 (sn1998s-19980316.000-hst.fits). ------------------------------------------------------------------------------------------------------------------------------------ 4 OFFSETSTAR STIS/CCD ACQ F28X50LP MIRROR 1 10 S (10 S) Comments: Used sn2008j-20080216.205-ui.flm (day 32 spectrum) normalized to V=16. SN should be bright during initial acquisition. Latest ETC calculation here: STIS.ta.1518260 ------------------------------------------------------------------------------------------------------------------------------------ 5 ZTF21AAABWZ STIS/NUV TIME-TA 52X0.5 G230L 2376 BUFFER-TIME=686 1 2500 S X -MAMA G see below (1989 S) ------------------------------------------------------------------------------------------------------------------------------------ 6 ZTF21AAABWZ STIS/NUV TIME-TA 52X0.5 G230L 2376 BUFFER-TIME=686 1 2500 S X -MAMA G see below (2736 S) ------------------------------------------------------------------------------------------------------------------------------------ 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 | ------------------------------------------------------------------------------------------------------------------------------------ OFFSETSTAR 1 STIS/CCD ACQ F28X50LP MIRROR none none none none 1 N/A ZTF21AAABWZX 2 STIS/FUV TIME-TA 52X0.5D1 G140L 1425 none none none none 1 2156.0 S -MAMA G ZTF21AAABWZX 3 STIS/FUV TIME-TA 52X0.5D1 G140L 1425 none none none none 2 2736.0 S -MAMA G OFFSETSTAR 4 STIS/CCD ACQ F28X50LP MIRROR none none none none 3 N/A ZTF21AAABWZX 5 STIS/NUV TIME-TA 52X0.5 G230L 2376 none none none none 3 1989.0 S -MAMA G ZTF21AAABWZX 6 STIS/NUV TIME-TA 52X0.5 G230L 2376 none none none none 4 2736.0 S -MAMA G 16189( 14) - 09-May-2023 14:31:55 - [ 21] Summary Form for Proposal 16189 Item Used in this proposal ------------------------------------------------------------------------------------------------------------------------------------ Apertures 52X0.5, 52X0.5D1, F28X50LP ------------------------------------------------------------------------------------------------------------------------------------ Configurations STIS/CCD, STIS/FUV-MAMA, STIS/NUV-MAMA ------------------------------------------------------------------------------------------------------------------------------------ Opmodes ACQ, TIME-TAG ------------------------------------------------------------------------------------------------------------------------------------ Optional Parameters BUFFER-TIME=3644, BUFFER-TIME=686 ------------------------------------------------------------------------------------------------------------------------------------ Special Requirements AFTER 02 BY 200 D TO 240 D, AFTER Z1 BY 50 D TO 80 D, ON HOLD , TOO RESPONSE TIME 21.0D ------------------------------------------------------------------------------------------------------------------------------------ Spectral Elements G140L, G230L, MIRROR ------------------------------------------------------------------------------------------------------------------------------------ Target Names OFFSETSTAR, ZTF21AAABWZX ------------------------------------------------------------------------------------------------------------------------------------