18073( 10) - 05-Mar-2026 19:03:37 - [ 1] HUBBLE SPACE TELESCOPE OBSERVING PROGRAM 18073 Version: 10 Check-in Time: 05-Mar-2026 19:03:37 STScI Edit Number: 4 Title Using Early FUV Spectra of Type IIP/L Supernovae to Elucidate Mass Loss in Red Supergiants ------------------------------------------------------------------------------------ Type Cycle GO 33 ------------------------------------------------------------------------------------ Investigators Contact? PI: Dr. Kyra Azalee Bostroem University of Arizona Y CoI: Dr. Jennifer Andrews NOIRLab - Gemini North (HI) N CoI: Dr. Yize Dong Harvard University N CoI: Emily Hoang University of California - Davis N CoI: Prof. Griffin Hosseinzadeh University of California - San Diego N CoI: Daryl Janzen University of Saskatchewan N CoI: Dr. Jacob Jencson California Institute of Technology N CoI: Dr. Saurabh W. Jha Rutgers the State University of New Jersey N CoI: Dr. Michael Jon Lundquist California Association for Research in N Astronomy (CARA) CoI: Ms. Darshana Mehta University of California - Davis N CoI: Mr. Nicolas Eduardo Meza Retamal University of California - Davis N CoI: Dr. Aravind Pazhayath Ravi University of California - Davis N CoI: Jeniveve Pearson University of Arizona N CoI: Prof. David J. Sand University of Arizona N CoI: Dr. Manisha Shrestha Monash University N CoI: Prof. Stefano Valenti University of California - Davis N CoI: Dr. Lindsey Kwok Northwestern University N ------------------------------------------------------------------------------------ Abstract Red supergiants, the progenitors of Type IIP/L supernovae lose a significant fraction of their initial mass during their lifetimes. However, there is no first-principle description of this mass loss and empirical prescriptions vary by orders of magnitude. On top of this uncertainty, recent optical supernova observations show periods of enhanced mass-loss occur just prior to explosion which are not described by any model. It is not known what fraction of red supergiants experience this kind of eruptive mass loss. While optical light curves and spectroscopy can probe the most extreme mass-loss rates, the UV is significantly more sensitive to interaction between the supernova ejecta and circumstellar material, probing mass-loss rates from nominal red supergiant winds to the strongest outbursts. Additionally, during the first week of evolution, while the optical is relatively featureless, the FUV is full of high-ioniztion and strong resonance lines which provide information about the metalicity of the progenitor star, temperature and density of the supernova ejecta, and the composition of the circumstellar material. These observations are also critical for interpreting the growing number of supernovae discovered at high redshift. However, early FUV observations are challenging: only ~1 infant supernova per year is observable with HST. In this proposal, we request a disruptive ToO observation to study a nearby, infant, Type IIP/L supernova in the FUV and NUV. These observations will map the final phases of red supergiant mass loss, connect them to the properties of the supernova and progenitor star, and shed light on the UV diversity of supernovae. ------------------------------------------------------------------------------------ 18073( 10) - 05-Mar-2026 19:03:37 - [ 2] Observations Description ------------------------ We will trigger this ToO on a Type II supernova that is UV bright and discovered within 24 hours of explosion. We would like the First visit to execute as soon as possible with the second visit executing a day later and the third visit a day after that. The final visit will execute 7 days after the last visit. We request a full GS acquisition at the beginning of each orbit of the first three visits as the supernova will change on the timescale of a day and thus these observations are not repeatable. We use a fixed target as a placeholder for the real target to easily vet the visibility of new candidates. The coordinates will be updated before the ToO trigger is submitted. ------------------------------------------------------------------------------------ 18073( 10) - 05-Mar-2026 19:03:37 - [ 3] TARGET LIST Fixed Targets ------------------------------------------------------------------------------------------------------------------------------------ Tar| Target | Target | Target |Coord | Radial | Flux data No | Name | Description | Position |Eqnx | Vel. | ------------------------------------------------------------------------------------------------------------------------------------ 1 SN2026AYT EXT-STAR, SUPERNOVA RA=09H27M23.3900S, J2000 V = 17 TYPE II DEC=-32D00'30.88" Reference Frame: ICRS Extended: NO Comments: This object was generated by the targetselector and retrieved from the SIMBAD database. Epoch of Position RA proper motion (seconds of time/yr) DEC Proper Motion (arcsec/yr) Annual Parallax (arcsec) 2000 0.0 0.0 0.0 ------------------------------------------------------------------------------------------------------------------------------------ 18073( 10) - 05-Mar-2026 19:03:37 - [ 4] Visit: 01 Visit Requirements: ON HOLD ; TOO RESPONSE TIME 2.0D On Hold Comments: Waiting for a suitable supernova to explode. I understand this response time is likely a lower limit on what STScI is capable of but the sooner the better for this program Additional Comments: Please put a full GS acq at the beginning of each orbit so if one orbit fails the others have a chance of succeeding. I can adjust the exposure times if needed First epoch should be executed as soon as possible after trigger For SN with initial brightness around r=17 mag 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 SN2026AYT STIS/CCD ACQ F28X50LP MIRROR 1 5 S (5 S) ------------------------------------------------------------------------------------------------------------------------------------ 2 SN2026AYT STIS/FUV ACCUM 52X0.2 G140L 1425 1 2000 S -MAMA (2000 S) ------------------------------------------------------------------------------------------------------------------------------------ 3 SN2026AYT STIS/CCD ACQ F28X50LP MIRROR 1 5 S (5 S) NEW OBSET FULL ACQ ------------------------------------------------------------------------------------------------------------------------------------ 4 SN2026AYT STIS/FUV ACCUM 52X0.2 G140L 1425 1 750 S (750 -MAMA S) ------------------------------------------------------------------------------------------------------------------------------------ 5 SN2026AYT STIS/NUV ACCUM 52X0.2 G230L 2376 1 750 S (750 -MAMA S) ------------------------------------------------------------------------------------------------------------------------------------ 6 SN2026AYT STIS/CCD ACQ F28X50LP MIRROR 1 5 S (5 S) NEW OBSET FULL ACQ ------------------------------------------------------------------------------------------------------------------------------------ 7 SN2026AYT STIS/NUV ACCUM 52X0.2 G230L 2376 1 790 S (790 -MAMA S) ------------------------------------------------------------------------------------------------------------------------------------ 8 SN2026AYT STIS/CCD ACCUM 52X0.2E1 G430L 4300 1 790 S (790 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 | ------------------------------------------------------------------------------------------------------------------------------------ SN2026AYT 1 STIS/CCD ACQ F28X50LP MIRROR none none none none 1 N/A SN2026AYT 2 STIS/FUV ACCUM 52X0.2 G140L 1425 none none none none 1 N/A -MAMA SN2026AYT 3 STIS/CCD ACQ F28X50LP MIRROR none none none none 2 N/A SN2026AYT 4 STIS/FUV ACCUM 52X0.2 G140L 1425 none none none none 2 N/A -MAMA SN2026AYT 5 STIS/NUV ACCUM 52X0.2 G230L 2376 none none none none 2 N/A -MAMA SN2026AYT 6 STIS/CCD ACQ F28X50LP MIRROR none none none none 3 N/A 18073( 10) - 05-Mar-2026 19:03:37 - [ 5] 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 | ------------------------------------------------------------------------------------------------------------------------------------ SN2026AYT 7 STIS/NUV ACCUM 52X0.2 G230L 2376 none none none none 3 N/A -MAMA SN2026AYT 8 STIS/CCD ACCUM 52X0.2E1 G430L 4300 none none none 1 3 N/A SN2026AYT 8 STIS/CCD ACCUM 52X0.2E1 G430L 4300 none none none 2 3 N/A 18073( 10) - 05-Mar-2026 19:03:37 - [ 6] Visit: 02 Visit Requirements: AFTER 01 BY 18 H TO 28 H; ON HOLD On Hold Comments: Waiting for a suitable supernova to explode. Additional Comments: Please put a full GS acq at the beginning of each orbit so if one orbit fails the others have a chance of succeeding. I can adjust the exposure times if needed Second epoch should be executed 24 hours after first visit For SN with initial brightness around r=17 mag If possible execute at same orientation as visit 1 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 SN2026AYT STIS/CCD ACQ F28X50LP MIRROR 1 5 S (5 S) ------------------------------------------------------------------------------------------------------------------------------------ 2 SN2026AYT STIS/FUV ACCUM 52X0.2 G140L 1425 1 2000 S -MAMA (2000 S) ------------------------------------------------------------------------------------------------------------------------------------ 3 SN2026AYT STIS/CCD ACQ F28X50LP MIRROR 1 5 S (5 S) NEW OBSET FULL ACQ ------------------------------------------------------------------------------------------------------------------------------------ 4 SN2026AYT STIS/FUV ACCUM 52X0.2 G140L 1425 1 750 S (750 -MAMA S) ------------------------------------------------------------------------------------------------------------------------------------ 5 SN2026AYT STIS/NUV ACCUM 52X0.2 G230L 2376 1 750 S (750 -MAMA S) ------------------------------------------------------------------------------------------------------------------------------------ 6 SN2026AYT STIS/CCD ACQ F28X50LP MIRROR 1 5 S (5 S) NEW OBSET FULL ACQ ------------------------------------------------------------------------------------------------------------------------------------ 7 SN2026AYT STIS/NUV ACCUM 52X0.2 G230L 2376 1 790 S (790 -MAMA S) ------------------------------------------------------------------------------------------------------------------------------------ 8 SN2026AYT STIS/CCD ACCUM 52X0.2E1 G430L 4300 1 790 S (790 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 | ------------------------------------------------------------------------------------------------------------------------------------ SN2026AYT 1 STIS/CCD ACQ F28X50LP MIRROR none none none none 1 N/A SN2026AYT 2 STIS/FUV ACCUM 52X0.2 G140L 1425 none none none none 1 N/A -MAMA SN2026AYT 3 STIS/CCD ACQ F28X50LP MIRROR none none none none 2 N/A SN2026AYT 4 STIS/FUV ACCUM 52X0.2 G140L 1425 none none none none 2 N/A -MAMA SN2026AYT 5 STIS/NUV ACCUM 52X0.2 G230L 2376 none none none none 2 N/A -MAMA SN2026AYT 6 STIS/CCD ACQ F28X50LP MIRROR none none none none 3 N/A 18073( 10) - 05-Mar-2026 19:03:37 - [ 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 | ------------------------------------------------------------------------------------------------------------------------------------ SN2026AYT 7 STIS/NUV ACCUM 52X0.2 G230L 2376 none none none none 3 N/A -MAMA SN2026AYT 8 STIS/CCD ACCUM 52X0.2E1 G430L 4300 none none none 1 3 N/A SN2026AYT 8 STIS/CCD ACCUM 52X0.2E1 G430L 4300 none none none 2 3 N/A 18073( 10) - 05-Mar-2026 19:03:37 - [ 8] Visit: 03 Visit Requirements: AFTER 02 BY 18 H TO 24 H; ON HOLD On Hold Comments: Waiting for a suitable supernova to explode. Additional Comments: Please put a full GS acq at the beginning of each orbit so if one orbit fails the others have a chance of succeeding. I can adjust the exposure times if needed Third epoch should be executed 24 hours after second visit and 48 hours after first visit For SN with initial brightness around r=17 mag If possible execute at same orientation as visit 1 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 SN2026AYT STIS/CCD ACQ F28X50LP MIRROR 1 2 S (2 S) ------------------------------------------------------------------------------------------------------------------------------------ 2 SN2026AYT STIS/FUV ACCUM 52X0.2 G140L 1425 1 2000 S -MAMA (2000 S) ------------------------------------------------------------------------------------------------------------------------------------ 3 SN2026AYT STIS/CCD ACQ F28X50LP MIRROR 1 2 S (2 S) NEW OBSET FULL ACQ ------------------------------------------------------------------------------------------------------------------------------------ 4 SN2026AYT STIS/NUV ACCUM 52X0.2 G230L 2376 1 1300 S -MAMA (1300 S) ------------------------------------------------------------------------------------------------------------------------------------ 5 SN2026AYT STIS/CCD ACCUM 52X0.2E1 G430L 4300 1 180 S (180 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 | ------------------------------------------------------------------------------------------------------------------------------------ SN2026AYT 1 STIS/CCD ACQ F28X50LP MIRROR none none none none 1 N/A SN2026AYT 2 STIS/FUV ACCUM 52X0.2 G140L 1425 none none none none 1 N/A -MAMA SN2026AYT 3 STIS/CCD ACQ F28X50LP MIRROR none none none none 2 N/A SN2026AYT 4 STIS/NUV ACCUM 52X0.2 G230L 2376 none none none none 2 N/A -MAMA SN2026AYT 5 STIS/CCD ACCUM 52X0.2E1 G430L 4300 none none none 1 2 N/A SN2026AYT 5 STIS/CCD ACCUM 52X0.2E1 G430L 4300 none none none 2 2 N/A 18073( 10) - 05-Mar-2026 19:03:37 - [ 9] Visit: 04 Visit Requirements: AFTER 03 BY 6 D TO 8 D; ON HOLD On Hold Comments: Waiting for a suitable supernova to explode. Additional Comments: Please put a full GS acq at the beginning of each orbit so if one orbit fails the others have a chance of succeeding. I can adjust the exposure times if needed fourth epoch should be executed 7 days after third visit For SN with initial brightness around r=17 mag If possible execute at same orientation as visit 1 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 SN2026AYT STIS/CCD ACQ F28X50LP MIRROR 1 5 S (5 S) ------------------------------------------------------------------------------------------------------------------------------------ 2 SN2026AYT STIS/FUV ACCUM 52X0.2 G140L 1425 1 2000 S -MAMA (2000 S) ------------------------------------------------------------------------------------------------------------------------------------ 3 SN2026AYT STIS/FUV ACCUM 52X0.2 G140L 1425 1 2500 S NEW OBSET FULL ACQ -MAMA (2500 S) ------------------------------------------------------------------------------------------------------------------------------------ 4 SN2026AYT STIS/FUV ACCUM 52X0.2 G140L 1425 1 2500 S NEW OBSET FULL ACQ -MAMA (2500 S) ------------------------------------------------------------------------------------------------------------------------------------ 5 SN2026AYT STIS/FUV ACCUM 52X0.2 G140L 1425 1 800 S (800 NEW OBSET FULL ACQ -MAMA S) ------------------------------------------------------------------------------------------------------------------------------------ 6 SN2026AYT STIS/NUV ACCUM 52X0.2 G230L 2376 1 740 S (740 -MAMA S) ------------------------------------------------------------------------------------------------------------------------------------ 7 SN2026AYT STIS/CCD ACCUM 52X0.2E1 G430L 4300 1 200 S (200 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 | ------------------------------------------------------------------------------------------------------------------------------------ SN2026AYT 1 STIS/CCD ACQ F28X50LP MIRROR none none none none 1 N/A SN2026AYT 2 STIS/FUV ACCUM 52X0.2 G140L 1425 none none none none 1 N/A -MAMA SN2026AYT 3 STIS/FUV ACCUM 52X0.2 G140L 1425 none none none none 2 N/A -MAMA SN2026AYT 4 STIS/FUV ACCUM 52X0.2 G140L 1425 none none none none 3 N/A -MAMA SN2026AYT 5 STIS/FUV ACCUM 52X0.2 G140L 1425 none none none none 4 N/A -MAMA SN2026AYT 6 STIS/NUV ACCUM 52X0.2 G230L 2376 none none none none 4 N/A -MAMA 18073( 10) - 05-Mar-2026 19:03:37 - [ 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 | ------------------------------------------------------------------------------------------------------------------------------------ SN2026AYT 7 STIS/CCD ACCUM 52X0.2E1 G430L 4300 none none none 1 4 N/A SN2026AYT 7 STIS/CCD ACCUM 52X0.2E1 G430L 4300 none none none 2 4 N/A 18073( 10) - 05-Mar-2026 19:03:37 - [ 11] Visit: 05 (Visit 1a) Visit Requirements: TOO RESPONSE TIME 2.0D On Hold Comments: Additional Comments: Please put a full GS acq at the beginning of each orbit so if one orbit fails the others have a chance of succeeding. I can adjust the exposure times if needed First epoch should be executed as soon as possible after trigger For SN with initial brightness around r=17 mag 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 SN2026AYT STIS/CCD ACQ F28X50LP MIRROR 1 5 S (5 S) ------------------------------------------------------------------------------------------------------------------------------------ 2 SN2026AYT STIS/FUV ACCUM 52X0.2 G140L 1425 1 2000 S -MAMA (2000 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 | ------------------------------------------------------------------------------------------------------------------------------------ SN2026AYT 1 STIS/CCD ACQ F28X50LP MIRROR none none none none 1 N/A SN2026AYT 2 STIS/FUV ACCUM 52X0.2 G140L 1425 none none none none 1 N/A -MAMA 18073( 10) - 05-Mar-2026 19:03:37 - [ 12] Visit: 06 (Visit 1b) Visit Requirements: AFTER 05 BY 0 H TO 8 H; TOO RESPONSE TIME 2.0D On Hold Comments: Additional Comments: Please put a full GS acq at the beginning of each orbit so if one orbit fails the others have a chance of succeeding. I can adjust the exposure times if needed First epoch should be executed as soon as possible after trigger For SN with initial brightness around r=17 mag 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 SN2026AYT STIS/CCD ACQ F28X50LP MIRROR 1 5 S (5 S) NEW OBSET FULL ACQ ------------------------------------------------------------------------------------------------------------------------------------ 2 SN2026AYT STIS/FUV ACCUM 52X0.2 G140L 1425 1 750 S (750 -MAMA S) ------------------------------------------------------------------------------------------------------------------------------------ 3 SN2026AYT STIS/NUV ACCUM 52X0.2 G230L 2376 1 750 S (750 -MAMA 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 | ------------------------------------------------------------------------------------------------------------------------------------ SN2026AYT 1 STIS/CCD ACQ F28X50LP MIRROR none none none none 1 N/A SN2026AYT 2 STIS/FUV ACCUM 52X0.2 G140L 1425 none none none none 1 N/A -MAMA SN2026AYT 3 STIS/NUV ACCUM 52X0.2 G230L 2376 none none none none 1 N/A -MAMA 18073( 10) - 05-Mar-2026 19:03:37 - [ 13] Visit: 07 (Visit 1c) Visit Requirements: AFTER 05 BY 0 H TO 8 H; TOO RESPONSE TIME 2.0D On Hold Comments: Additional Comments: Please put a full GS acq at the beginning of each orbit so if one orbit fails the others have a chance of succeeding. I can adjust the exposure times if needed First epoch should be executed as soon as possible after trigger For SN with initial brightness around r=17 mag 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 SN2026AYT STIS/CCD ACQ F28X50LP MIRROR 1 5 S (5 S) NEW OBSET FULL ACQ ------------------------------------------------------------------------------------------------------------------------------------ 2 SN2026AYT STIS/NUV ACCUM 52X0.2 G230L 2376 1 790 S (790 -MAMA S) ------------------------------------------------------------------------------------------------------------------------------------ 3 SN2026AYT STIS/CCD ACCUM 52X0.2E1 G430L 4300 1 790 S (790 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 | ------------------------------------------------------------------------------------------------------------------------------------ SN2026AYT 1 STIS/CCD ACQ F28X50LP MIRROR none none none none 1 N/A SN2026AYT 2 STIS/NUV ACCUM 52X0.2 G230L 2376 none none none none 1 N/A -MAMA SN2026AYT 3 STIS/CCD ACCUM 52X0.2E1 G430L 4300 none none none 1 1 N/A SN2026AYT 3 STIS/CCD ACCUM 52X0.2E1 G430L 4300 none none none 2 1 N/A 18073( 10) - 05-Mar-2026 19:03:37 - [ 14] Visit: 08 (Visit 2a) Visit Requirements: AFTER 05 BY 18 H TO 28 H On Hold Comments: Additional Comments: Please put a full GS acq at the beginning of each orbit so if one orbit fails the others have a chance of succeeding. I can adjust the exposure times if needed Second epoch should be executed 24 hours after first visit For SN with initial brightness around r=17 mag If possible execute at same orientation as visit 1 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 SN2026AYT STIS/CCD ACQ F28X50LP MIRROR 1 5 S (5 S) ------------------------------------------------------------------------------------------------------------------------------------ 2 SN2026AYT STIS/FUV ACCUM 52X0.2 G140L 1425 1 2000 S -MAMA (2000 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 | ------------------------------------------------------------------------------------------------------------------------------------ SN2026AYT 1 STIS/CCD ACQ F28X50LP MIRROR none none none none 1 N/A SN2026AYT 2 STIS/FUV ACCUM 52X0.2 G140L 1425 none none none none 1 N/A -MAMA 18073( 10) - 05-Mar-2026 19:03:37 - [ 15] Visit: 09 (Visit 2b) Visit Requirements: AFTER 08 BY 0 H TO 8 H On Hold Comments: Additional Comments: Please put a full GS acq at the beginning of each orbit so if one orbit fails the others have a chance of succeeding. I can adjust the exposure times if needed Second epoch should be executed 24 hours after first visit For SN with initial brightness around r=17 mag If possible execute at same orientation as visit 1 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 SN2026AYT STIS/CCD ACQ F28X50LP MIRROR 1 5 S (5 S) NEW OBSET FULL ACQ ------------------------------------------------------------------------------------------------------------------------------------ 2 SN2026AYT STIS/FUV ACCUM 52X0.2 G140L 1425 1 750 S (750 -MAMA S) ------------------------------------------------------------------------------------------------------------------------------------ 3 SN2026AYT STIS/NUV ACCUM 52X0.2 G230L 2376 1 750 S (750 -MAMA 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 | ------------------------------------------------------------------------------------------------------------------------------------ SN2026AYT 1 STIS/CCD ACQ F28X50LP MIRROR none none none none 1 N/A SN2026AYT 2 STIS/FUV ACCUM 52X0.2 G140L 1425 none none none none 1 N/A -MAMA SN2026AYT 3 STIS/NUV ACCUM 52X0.2 G230L 2376 none none none none 1 N/A -MAMA 18073( 10) - 05-Mar-2026 19:03:37 - [ 16] Visit: 10 (Visit 2c) Visit Requirements: AFTER 08 BY 0 H TO 8 H On Hold Comments: Additional Comments: Please put a full GS acq at the beginning of each orbit so if one orbit fails the others have a chance of succeeding. I can adjust the exposure times if needed Second epoch should be executed 24 hours after first visit For SN with initial brightness around r=17 mag If possible execute at same orientation as visit 1 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 SN2026AYT STIS/CCD ACQ F28X50LP MIRROR 1 5 S (5 S) NEW OBSET FULL ACQ ------------------------------------------------------------------------------------------------------------------------------------ 2 SN2026AYT STIS/NUV ACCUM 52X0.2 G230L 2376 1 790 S (790 -MAMA S) ------------------------------------------------------------------------------------------------------------------------------------ 3 SN2026AYT STIS/CCD ACCUM 52X0.2E1 G430L 4300 1 790 S (790 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 | ------------------------------------------------------------------------------------------------------------------------------------ SN2026AYT 1 STIS/CCD ACQ F28X50LP MIRROR none none none none 1 N/A SN2026AYT 2 STIS/NUV ACCUM 52X0.2 G230L 2376 none none none none 1 N/A -MAMA SN2026AYT 3 STIS/CCD ACCUM 52X0.2E1 G430L 4300 none none none 1 1 N/A SN2026AYT 3 STIS/CCD ACCUM 52X0.2E1 G430L 4300 none none none 2 1 N/A 18073( 10) - 05-Mar-2026 19:03:37 - [ 17] Visit: 11 (Visit 3a) Visit Requirements: AFTER 08 BY 18 H TO 24 H On Hold Comments: Additional Comments: Please put a full GS acq at the beginning of each orbit so if one orbit fails the others have a chance of succeeding. I can adjust the exposure times if needed Third epoch should be executed 24 hours after second visit and 48 hours after first visit For SN with initial brightness around r=17 mag If possible execute at same orientation as visit 1 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 SN2026AYT STIS/CCD ACQ F28X50LP MIRROR 1 2 S (2 S) ------------------------------------------------------------------------------------------------------------------------------------ 2 SN2026AYT STIS/FUV ACCUM 52X0.2 G140L 1425 1 2000 S -MAMA (2000 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 | ------------------------------------------------------------------------------------------------------------------------------------ SN2026AYT 1 STIS/CCD ACQ F28X50LP MIRROR none none none none 1 N/A SN2026AYT 2 STIS/FUV ACCUM 52X0.2 G140L 1425 none none none none 1 N/A -MAMA 18073( 10) - 05-Mar-2026 19:03:37 - [ 18] Visit: 12 (Visit 3b) Visit Requirements: AFTER 11 BY 0 H TO 8 H On Hold Comments: Additional Comments: Please put a full GS acq at the beginning of each orbit so if one orbit fails the others have a chance of succeeding. I can adjust the exposure times if needed Third epoch should be executed 24 hours after second visit and 48 hours after first visit For SN with initial brightness around r=17 mag If possible execute at same orientation as visit 1 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 SN2026AYT STIS/CCD ACQ F28X50LP MIRROR 1 2 S (2 S) NEW OBSET FULL ACQ ------------------------------------------------------------------------------------------------------------------------------------ 2 SN2026AYT STIS/NUV ACCUM 52X0.2 G230L 2376 1 1300 S -MAMA (1300 S) ------------------------------------------------------------------------------------------------------------------------------------ 3 SN2026AYT STIS/CCD ACCUM 52X0.2E1 G430L 4300 1 180 S (180 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 | ------------------------------------------------------------------------------------------------------------------------------------ SN2026AYT 1 STIS/CCD ACQ F28X50LP MIRROR none none none none 1 N/A SN2026AYT 2 STIS/NUV ACCUM 52X0.2 G230L 2376 none none none none 1 N/A -MAMA SN2026AYT 3 STIS/CCD ACCUM 52X0.2E1 G430L 4300 none none none 1 1 N/A SN2026AYT 3 STIS/CCD ACCUM 52X0.2E1 G430L 4300 none none none 2 1 N/A 18073( 10) - 05-Mar-2026 19:03:37 - [ 19] Visit: 13 (Visit 4a) Visit Requirements: AFTER 11 BY 6 D TO 8 D On Hold Comments: Additional Comments: Please put a full GS acq at the beginning of each orbit so if one orbit fails the others have a chance of succeeding. I can adjust the exposure times if needed fourth epoch should be executed 7 days after third visit For SN with initial brightness around r=17 mag If possible execute at same orientation as visit 1 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 SN2026AYT STIS/CCD ACQ F28X50LP MIRROR 1 5 S (5 S) ------------------------------------------------------------------------------------------------------------------------------------ 2 SN2026AYT STIS/FUV ACCUM 52X0.2 G140L 1425 1 2000 S -MAMA (2000 S) ------------------------------------------------------------------------------------------------------------------------------------ 3 SN2026AYT STIS/FUV ACCUM 52X0.2 G140L 1425 1 2500 S NEW OBSET FULL ACQ -MAMA (2500 S) ------------------------------------------------------------------------------------------------------------------------------------ 4 SN2026AYT STIS/FUV ACCUM 52X0.2 G140L 1425 1 2500 S NEW OBSET FULL ACQ -MAMA (2500 S) ------------------------------------------------------------------------------------------------------------------------------------ 5 SN2026AYT STIS/FUV ACCUM 52X0.2 G140L 1425 1 800 S (800 NEW OBSET FULL ACQ -MAMA S) ------------------------------------------------------------------------------------------------------------------------------------ 6 SN2026AYT STIS/NUV ACCUM 52X0.2 G230L 2376 1 740 S (740 -MAMA S) ------------------------------------------------------------------------------------------------------------------------------------ 7 SN2026AYT STIS/CCD ACCUM 52X0.2E1 G430L 4300 1 200 S (200 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 | ------------------------------------------------------------------------------------------------------------------------------------ SN2026AYT 1 STIS/CCD ACQ F28X50LP MIRROR none none none none 1 N/A SN2026AYT 2 STIS/FUV ACCUM 52X0.2 G140L 1425 none none none none 1 N/A -MAMA SN2026AYT 3 STIS/FUV ACCUM 52X0.2 G140L 1425 none none none none 2 N/A -MAMA SN2026AYT 4 STIS/FUV ACCUM 52X0.2 G140L 1425 none none none none 3 N/A -MAMA SN2026AYT 5 STIS/FUV ACCUM 52X0.2 G140L 1425 none none none none 4 N/A -MAMA SN2026AYT 6 STIS/NUV ACCUM 52X0.2 G230L 2376 none none none none 4 N/A -MAMA 18073( 10) - 05-Mar-2026 19:03:37 - [ 20] 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 | ------------------------------------------------------------------------------------------------------------------------------------ SN2026AYT 7 STIS/CCD ACCUM 52X0.2E1 G430L 4300 none none none 1 4 N/A SN2026AYT 7 STIS/CCD ACCUM 52X0.2E1 G430L 4300 none none none 2 4 N/A 18073( 10) - 05-Mar-2026 19:03:37 - [ 21] Visit: 14 (Visit 4 NUV only) Visit Requirements: VISIBILITY INTERVAL 43 M On Hold Comments: Additional Comments: NUV only visit if this cannot be scheduled until later 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 SN2026AYT STIS/CCD ACQ F28X50LP MIRROR 1 5 S (5 S) ------------------------------------------------------------------------------------------------------------------------------------ 2 SN2026AYT STIS/NUV ACCUM 52X0.2 G230L 2376 1 1710 S -MAMA (1710 S) ------------------------------------------------------------------------------------------------------------------------------------ 3 SN2026AYT STIS/NUV ACCUM 52X0.2 G230L 2376 1 2180 S -MAMA (2180 S) ------------------------------------------------------------------------------------------------------------------------------------ 4 SN2026AYT STIS/NUV ACCUM 52X0.2 G230L 2376 1 2180 S -MAMA (2180 S) ------------------------------------------------------------------------------------------------------------------------------------ 5 SN2026AYT STIS/NUV ACCUM 52X0.2 G230L 2376 1 1680 S -MAMA (1680 S) ------------------------------------------------------------------------------------------------------------------------------------ 6 SN2026AYT STIS/CCD ACCUM 52X0.2E1 G430L 4300 1 200 S (200 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 | ------------------------------------------------------------------------------------------------------------------------------------ SN2026AYT 1 STIS/CCD ACQ F28X50LP MIRROR none none none none 1 N/A SN2026AYT 2 STIS/NUV ACCUM 52X0.2 G230L 2376 none none none none 1 N/A -MAMA SN2026AYT 3 STIS/NUV ACCUM 52X0.2 G230L 2376 none none none none 2 N/A -MAMA SN2026AYT 4 STIS/NUV ACCUM 52X0.2 G230L 2376 none none none none 3 N/A -MAMA SN2026AYT 5 STIS/NUV ACCUM 52X0.2 G230L 2376 none none none none 4 N/A -MAMA SN2026AYT 6 STIS/CCD ACCUM 52X0.2E1 G430L 4300 none none none 1 4 N/A SN2026AYT 6 STIS/CCD ACCUM 52X0.2E1 G430L 4300 none none none 2 4 N/A 18073( 10) - 05-Mar-2026 19:03:37 - [ 22] Summary Form for Proposal 18073 Item Used in this proposal ------------------------------------------------------------------------------------------------------------------------------------ Apertures 52X0.2, 52X0.2E1, F28X50LP ------------------------------------------------------------------------------------------------------------------------------------ Configurations STIS/CCD, STIS/FUV-MAMA, STIS/NUV-MAMA ------------------------------------------------------------------------------------------------------------------------------------ Opmodes ACCUM, ACQ ------------------------------------------------------------------------------------------------------------------------------------ Optional Parameters ------------------------------------------------------------------------------------------------------------------------------------ Special Requirements AFTER 01 BY 18 H TO 28 H, AFTER 02 BY 18 H TO 24 H, AFTER 03 BY 6 D TO 8 D, AFTER 05 BY 0 H TO 8 H, AFTER 05 BY 18 H TO 28 H, AFTER 08 BY 0 H TO 8 H, AFTER 08 BY 18 H TO 24 H, AFTER 11 BY 0 H TO 8 H, AFTER 11 BY 6 D TO 8 D, NEW OBSET FULL ACQ, ON HOLD , TOO RESPONSE TIME 2.0D, VISIBILITY INTERVAL 43 M ------------------------------------------------------------------------------------------------------------------------------------ Spectral Elements G140L, G230L, G430L, MIRROR ------------------------------------------------------------------------------------------------------------------------------------ Target Names SN2026AYT ------------------------------------------------------------------------------------------------------------------------------------