17195( 7) - 29-Sep-2023 20:56:01 - [ 1] HUBBLE SPACE TELESCOPE OBSERVING PROGRAM 17195 Version: 7 Check-in Time: 29-Sep-2023 20:56:01 STScI Edit Number: 4 Title UV Spectroscopic Signatures from Fast Evolving Transients ------------------------------------------------------------------------------------ Type Cycle GO 30 ------------------------------------------------------------------------------------ Investigators Contact? PI: Dr. Ori Dosovitz Fox Space Telescope Science Institute Y CoI: Dr. Jennifer Andrews NOIRLab - Gemini North (HI) N CoI: Dr. Thomas G Brink University of California - Berkeley N CoI: Dr. Peter J. Brown Texas A & M University N CoI: Dr. Roger A. Chevalier The University of Virginia N CoI: Dr. Geoffrey C. Clayton Space Science Institute N CoI: Prof. Alex V. Filippenko University of California - Berkeley N CoI: Prof. Claes Fransson Stockholm University N CoI: Dr. Jose Groh University of Dublin, Trinity College N CoI: Dr. Griffin Hosseinzadeh University of Arizona N CoI: Dr. Patrick Kelly University of Minnesota - Twin Cities N CoI: Dr. Nathan Smith University of Arizona N CoI: Dr. Tamas Szalai University of Szeged N CoI: Dr. Schuyler D. Van Dyk California Institute of Technology N CoI: Dr. WeiKang Zheng University of California - Berkeley N CoI: Dr. Sebastian Gomez Space Telescope Science Institute N CoI: Dr. Saurabh W. Jha Rutgers the State University of New Jersey N CoI: Dr. Mi Dai The Johns Hopkins University N CoI: Dr. Chelsea Harris Michigan State University N CoI: Dr. Luc Dessart CNRS, Institut d'Astrophysique de Paris N CoI: Dr. Melissa Shahbandeh Space Telescope Science Institute N CoI: Dr. Yossef Zenati The Johns Hopkins University N CoI: Dr. Justin Pierel Space Telescope Science Institute N CoI: Mr. Qinan Wang The Johns Hopkins University N ------------------------------------------------------------------------------------ Abstract A new subclass of fast rising and fading transients is being uncovered as higher cadence all-sky surveys come online (e.g., ZTF, YSE), including FBOTs and supernovae (SNe) Type Ibn/Icn. This subclass generally tends to be described as "extreme" given they are some of the hottest, bluest, most luminous, and fastest evolving transients known, defying our current understanding of stellar evolution and explosions. While shock interaction with a dense circumstellar medium is likely, other powering mechanisms may be at play. Yet compared to other SNe, very little is known about these events. One of the reasons is that the optical spectra tend to be dominated by a featureless continuum. The UV, however, provides an important window by which to study these events, as a significant amount of energy emerges at these wavelengths and a multitude of emission lines probe the abundances of both iron-group and intermediate-mass elements. Recent advances in theoretical models (CMFGEN, specifically) now allow for the treatment of these fast transients, including in the UV. While several UV spectra exist, they do not adequately span the known diversity of this subclass. Furthermore, they tend not to be obtained early enough relative to peak to build a complete model of the event (e.g. CSM composition and mass, 17195( 7) - 29-Sep-2023 20:56:01 - [ 2] energetics). Published spectra offer qualitative comparisons, but do not perform any detailed modeling. Here we propose a disruptive ToO with HST/STIS to obtain 2 epochs of UV spectra of a fast transient within 250 Mpc. Follow-up modeling will result in a detailed probe of mass-loss history and powering mechanism in this extreme(!) new subclass. ------------------------------------------------------------------------------------ Observations Description ------------------------ We propose to obtain 2 epochs (3 orbits each) of STIS-MAMA spectra of a single Fast Transient supernova. The brightness is really the most important factor, but fast transients can vary in brightness substantially (magnitudes). We offer rough guidelines of a target within 250 Mpc and as close to light-curve maximum as possible. The goal is to detect UV signatures that can distinguish between 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 *disruptive* ToO, and observations should be scheduled as soon as possible. The second epoch should be obtained again within 10 days (the goal is to maximize the time between the two epochs, so there may be some wiggle room depending on the brightness and evolution timeline of the SN). We will use the data to trace circumstellar interaction, constrain the progenitor mass loss, and measure the CNO processing. Comparisons to other SN and FBOT subclasses will also help distinguish between progenitor systems and central engine powering mechanisms. The first epoch will include observations in both the G140 and G230L bandpasses. The second epoch will include observations in only the G230L bandpass. 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. ------------------------------------------------------------------------------------ 17195( 7) - 29-Sep-2023 20:56:01 - [ 3] TARGET LIST Fixed Targets ------------------------------------------------------------------------------------------------------------------------------------ Tar| Target | Target | Target |Coord | Radial | Flux data No | Name | Description | Position |Eqnx | Vel. | ------------------------------------------------------------------------------------------------------------------------------------ 1 AT-2023TSV STAR, SUPERNOVA RA=08H37M29.5230S, J2000 V = 17.5 DEC=-00D02'35.70" Reference Frame: ICRS Extended: NO ------------------------------------------------------------------------------------------------------------------------------------ 17195( 7) - 29-Sep-2023 20:56:01 - [ 4] Patterns ------------------------------------------------------------------------------------------------------------------------------------ Pattern_Number: 1 Primary_Pattern Secondary_Pattern Pattern_Type STIS-ALONG-SLIT Pattern_Purpose DITHER Number_Of_Points 2 Point_Spacing 0.264 Line_Spacing Coordinate_Frame POS-TARG Pattern_Orient 90.0 Angle_Between_Sides Center_Pattern YES ------------------------------------------------------------------------------------------------------------------------------------ 17195( 7) - 29-Sep-2023 20:56:01 - [ 5] Visit: 01 (STIS-SN2023tsz-Epoch1 (NUV)) Visit Requirements: ON HOLD ; TOO RESPONSE TIME 2.0D On Hold Comments: Target-of-Opportunity. The initial spectrum will be triggered as a disruptive ToO, and observations should be scheduled as soon as possible (2-5 days as stated in the CfP). Less than 2 days could be possible since PI Fox works at STScI and has worked on ultra-rapid responses with HST planners in the past. The main goal, however, is to make sure the observations are obtained around peak, which typically happens about 3 days post-discovery. 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 AT-2023TSV STIS/CCD ACQ F28X50LP MIRROR 1 30 S (30 S) Comments: Used 10, 000K Blackbody normalized to V=16. SN should be bright during initial acquisition. ------------------------------------------------------------------------------------------------------------------------------------ 2 AT-2023TSV STIS/NUV ACCUM 52X0.2 G230L 2376 1 2000 S -MAMA see below (2104 S) Comments: Assuming a 10, 000K Blackbody around peak. ------------------------------------------------------------------------------------------------------------------------------------ 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 | ------------------------------------------------------------------------------------------------------------------------------------ AT-2023TSV 1 STIS/CCD ACQ F28X50LP MIRROR none none none none 1 N/A AT-2023TSV 2 STIS/NUV ACCUM 52X0.2 G230L 2376 none none none none 1 2104.0 S -MAMA 17195( 7) - 29-Sep-2023 20:56:01 - [ 6] Visit: 02 (STIS-SN2023tsz-Epoch1 (FUV)) Visit Requirements: AFTER 01 BY 0 Orbits TO 1.1 Orbits; ON HOLD ; TOO RESPONSE TIME 2.0D On Hold Comments: Target-of-Opportunity. The initial spectrum will be triggered as a disruptive ToO, and observations should be scheduled as soon as possible (2-5 days as stated in the CfP). Less than 2 days could be possible since PI Fox works at STScI and has worked on ultra-rapid responses with HST planners in the past. The main goal, however, is to make sure the observations are obtained around peak, which typically happens about 3 days post-discovery. 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 AT-2023TSV STIS/CCD ACQ F28X50LP MIRROR 1 30 S (30 S) Comments: Used 10, 000K Blackbody normalized to V=16. SN should be bright during initial acquisition. ------------------------------------------------------------------------------------------------------------------------------------ 2 AT-2023TSV STIS/FUV ACCUM 52X0.2D1 G140L 1425 1 2000 S -MAMA see below (2104 S) Comments: Assuming a 10, 000K Blackbody around peak. ------------------------------------------------------------------------------------------------------------------------------------ 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 | ------------------------------------------------------------------------------------------------------------------------------------ AT-2023TSV 1 STIS/CCD ACQ F28X50LP MIRROR none none none none 1 N/A AT-2023TSV 2 STIS/FUV ACCUM 52X0.2D1 G140L 1425 none none none none 1 2104.0 S -MAMA 17195( 7) - 29-Sep-2023 20:56:01 - [ 7] Visit: 03 (STIS-SN2023tsz-Epoch1 (FUV)) Visit Requirements: AFTER 02 BY 0 Orbits TO 1.1 Orbits; ON HOLD ; TOO RESPONSE TIME 2.0D On Hold Comments: Target-of-Opportunity. The initial spectrum will be triggered as a disruptive ToO, and observations should be scheduled as soon as possible (2-5 days as stated in the CfP). Less than 2 days could be possible since PI Fox works at STScI and has worked on ultra-rapid responses with HST planners in the past. The main goal, however, is to make sure the observations are obtained around peak, which typically happens about 3 days post-discovery. 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 AT-2023TSV STIS/CCD ACQ F28X50LP MIRROR 1 30 S (30 S) Comments: Used 10, 000K Blackbody normalized to V=16. SN should be bright during initial acquisition. ------------------------------------------------------------------------------------------------------------------------------------ 2 AT-2023TSV STIS/FUV ACCUM 52X0.2D1 G140L 1425 1 2000 S -MAMA see below (2104 S) Comments: Assuming a 10, 000K Blackbody around peak. ------------------------------------------------------------------------------------------------------------------------------------ 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 | ------------------------------------------------------------------------------------------------------------------------------------ AT-2023TSV 1 STIS/CCD ACQ F28X50LP MIRROR none none none none 1 N/A AT-2023TSV 2 STIS/FUV ACCUM 52X0.2D1 G140L 1425 none none none none 1 2104.0 S -MAMA 17195( 7) - 29-Sep-2023 20:56:01 - [ 8] Visit: 04 (STIS-SN2023tsz-Epoch2 (NUV)) Visit Requirements: AFTER 01 BY 6 D TO 12 D; ON HOLD On Hold Comments: Target-of-Opportunity. This visit will be scheduled for 6-12 days following the first visit (as specified in the Timing Requirements), ideally aiming for 10 days. But we'd like to have some flexibility with our final submission to account for the brightness and light-curve evolution. 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 AT-2023TSV STIS/CCD ACQ F28X50LP MIRROR 1 30 S (30 S) Comments: Used 10, 000K Blackbody normalized to V=16. SN should be bright during initial acquisition. ------------------------------------------------------------------------------------------------------------------------------------ 2 AT-2023TSV STIS/NUV ACCUM 52X0.2 G230L 2376 1 2000 S -MAMA see below (2104 S) Comments: Assuming a 7, 000K Blackbody around 10 days post-max. ------------------------------------------------------------------------------------------------------------------------------------ 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 | ------------------------------------------------------------------------------------------------------------------------------------ AT-2023TSV 1 STIS/CCD ACQ F28X50LP MIRROR none none none none 1 N/A AT-2023TSV 2 STIS/NUV ACCUM 52X0.2 G230L 2376 none none none none 1 2104.0 S -MAMA 17195( 7) - 29-Sep-2023 20:56:01 - [ 9] Visit: 05 (STIS-SN2023tsz-Epoch2 (NUV)) Visit Requirements: AFTER 04 BY 0 Orbits TO 1.1 Orbits; ON HOLD On Hold Comments: Target-of-Opportunity. This visit will be scheduled for 6-12 days following the first visit (as specified in the Timing Requirements), ideally aiming for 10 days. But we'd like to have some flexibility with our final submission to account for the brightness and light-curve evolution. 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 AT-2023TSV STIS/CCD ACQ F28X50LP MIRROR 1 30 S (30 S) Comments: Used 10, 000K Blackbody normalized to V=16. SN should be bright during initial acquisition. ------------------------------------------------------------------------------------------------------------------------------------ 2 AT-2023TSV STIS/NUV ACCUM 52X0.2 G230L 2376 1 2000 S -MAMA see below (2104 S) Comments: Assuming a 7, 000K Blackbody around 10 days post-max. ------------------------------------------------------------------------------------------------------------------------------------ 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 | ------------------------------------------------------------------------------------------------------------------------------------ AT-2023TSV 1 STIS/CCD ACQ F28X50LP MIRROR none none none none 1 N/A AT-2023TSV 2 STIS/NUV ACCUM 52X0.2 G230L 2376 none none none none 1 2104.0 S -MAMA 17195( 7) - 29-Sep-2023 20:56:01 - [ 10] Visit: 06 (STIS-SN2023tsz-Epoch2 (NUV)) Visit Requirements: AFTER 05 BY 0 Orbits TO 1.1 Orbits; ON HOLD On Hold Comments: Target-of-Opportunity. This visit will be scheduled for 6-12 days following the first visit (as specified in the Timing Requirements), ideally aiming for 10 days. But we'd like to have some flexibility with our final submission to account for the brightness and light-curve evolution. 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 AT-2023TSV STIS/CCD ACQ F28X50LP MIRROR 1 30 S (30 S) Comments: Used 10, 000K Blackbody normalized to V=16. SN should be bright during initial acquisition. ------------------------------------------------------------------------------------------------------------------------------------ 2 AT-2023TSV STIS/NUV ACCUM 52X0.2 G230L 2376 1 2000 S -MAMA see below (2104 S) Comments: Assuming a 7, 000K Blackbody around 10 days post-max. ------------------------------------------------------------------------------------------------------------------------------------ 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 | ------------------------------------------------------------------------------------------------------------------------------------ AT-2023TSV 1 STIS/CCD ACQ F28X50LP MIRROR none none none none 1 N/A AT-2023TSV 2 STIS/NUV ACCUM 52X0.2 G230L 2376 none none none none 1 2104.0 S -MAMA 17195( 7) - 29-Sep-2023 20:56:01 - [ 11] Summary Form for Proposal 17195 Item Used in this proposal ------------------------------------------------------------------------------------------------------------------------------------ Apertures 52X0.2, 52X0.2D1, F28X50LP ------------------------------------------------------------------------------------------------------------------------------------ Configurations STIS/CCD, STIS/FUV-MAMA, STIS/NUV-MAMA ------------------------------------------------------------------------------------------------------------------------------------ Opmodes ACCUM, ACQ ------------------------------------------------------------------------------------------------------------------------------------ Optional Parameters ------------------------------------------------------------------------------------------------------------------------------------ Special Requirements AFTER 01 BY 0 Orbits TO 1.1 Orbits, AFTER 01 BY 6 D TO 12 D, AFTER 02 BY 0 Orbits TO 1.1 Orbits, AFTER 04 BY 0 Orbits TO 1.1 Orbits, AFTER 05 BY 0 Orbits TO 1.1 Orbits, ON HOLD , TOO RESPONSE TIME 2.0D ------------------------------------------------------------------------------------------------------------------------------------ Spectral Elements G140L, G230L, MIRROR ------------------------------------------------------------------------------------------------------------------------------------ Target Names AT-2023TSV ------------------------------------------------------------------------------------------------------------------------------------