Target SN1: There is no need or capability to test the scheduling of observations of generic targets in Phase I. This warning will go away the next time the proposal is loaded. 0 Assigned ID: 5672 ----- Attempting Submission 1 (Tue Mar 26 21:22:40 GMT 2024) ----- HST Phase I Proposal 5672 successfully submitted. Receipt: # 5672-1 ----- Attempting Submission 2 (Tue Mar 26 21:58:38 GMT 2024) ----- HST Phase I Proposal 5672 successfully submitted. Receipt: # 5672-2 ----- Attempting Submission 3 (Tue Mar 26 22:13:03 GMT 2024) ----- HST Phase I Proposal 5672 successfully submitted. Receipt: # 5672-3 ----- Attempting Submission 4 (Tue Mar 26 22:37:13 GMT 2024) ----- HST Phase I Proposal 5672 successfully submitted. Receipt: # 5672-4 ----- Attempting Submission 5 (Tue Mar 26 23:50:26 GMT 2024) ----- HST Phase I Proposal 5672 successfully submitted. Receipt: # 5672-5 ----- Attempting Submission 6 (Tue Mar 26 23:59:26 GMT 2024) ----- ToO Genertic Targets Ok, we're going to trigger on this one. 732050188 ----- Attempting Submission 1 (Fri Aug 16 13:47:54 GMT 2024) ----- ----- Attempting Submission 2 (Tue Aug 05 13:28:06 GMT 2025) ----- HST Phase II Proposal 17814 successfully submitted. Receipt: # 17814-2 ----- Attempting Submission 4 (Fri Aug 08 14:47:42 GMT 2025) ----- Over the past decade, higher cadence all-sky surveys have uncovered a new, extreme class of transients with rapidly evolving light curves and high peak luminosities. The characteristics of these transients challenge our conventional understanding of massive star evolution and core-collapse supernovae (SNe). Most proposed models require a compact progenitor with extreme mass-loss, but the nature of both the progenitor and the mass-loss mechanism in these models does not often conform to conventional stellar evolution scenarios. UV spectra can offer important constraints on these models. They contain a significant fraction of the total energy output, uniquely probe thermal shock radiation that is not present at optical wavelengths, and directly trace the mass-loss history through P Cygni absorption profiles in the UV resonance lines. Over the past few years, the transient community has ramped up efforts to both collect UV spectra of fast transients and update spectroscopic modeling software (i.e., CMFGEN) to handle the physical scenarios associated with this subclass. Yet, to date, only a few UV spectra exist, and only the Type Ibn SN 2020nxt was successfully modeled by CMFGEN at UV wavelengths. Furthermore, within this SN Ibn subclass, there is known spectroscopic diversity amongst the events. Here we propose a disruptive ToO with HST/STIS to obtain 2 epochs of UV spectra of a fast transient that is within 250 Mpc. We will implement detailed CMFGEN modeling to constrain the progenitor system and pre-explosion mass-loss history. This program is not appropriate for ``Flex Thursday'' as the rates are too low. 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 roughly 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. Important Note: COS, however, will be sufficient in the case that STIS is unavailable in the aging spacecraft. Our team consists of experts ranging from theory to observation. We describe each team member's strength below. PI Dr. Ori Fox is an expert in SNe with shock interaction. He was the first author of Fox & Smith (2019), which linked SNe Ibn to FBOTs. He has extensive experience with HST and has previously obtained HST UV spectra. A COS UV spectrum of SN 1993J resulted in Fox et al. (2014), a popular paper that detected the first surviving companion to a SN progenitor. He has also successfully obtained STIS spectra of two SNe IIn (2005ip and 2010jl). This work has resulted in a paper that is very near to submission to ApJ. For theory, modeling, and interpretation: Dr. Luc Dessart is the leading expert in CMFGEN modeling and has written numerous papers on modeling interacting SNe (Dessart et al. 2011, 2018, 2019, 2022). Professor Roger Chevalier is an expert in modeling SN shock interaction with the circumstellar medium. Professor Claes Fransson is an expert in modeling SN shock interaction. He led papers on STIS spectra of several SNe IIn (Fransson et al., 2002, 2005, 2014). Dr. Chelsea Harris has significant experience modeling interacting SNe (Harris et al. 2020, 2021). Dr. Yossef Zenati has significant experience modeling interacting SNe (Zenati et al. 2020, 2021). For observation, data reduction, and analysis: Dr. Jennifer Andrews is an expert observer. With approved time on MMT, she will lead ground-based MMT spectroscopic observations, reduction, and analysis; assessment of spectral features indicative of interstellar extinction. Dr. Tom Brink has much experience obtaining and reducing ground-based spectra, and complementary data of this type will be obtained for the program. Dr. Peter Brown is an expert in Swift UV photometry and spectroscopy of SNe. He will be leading the Swift photometry follow-up portion of this project. Professor Geoffrey Clayton is an expert in modeling SN shock interaction. Professor Alex Filippenko has approved time on Keck and Lick that can provide for any necessary supporting ground-based observations. Dr. Griffin Hosseinzadeh is an expert in SNe Ibn. He wrote the recent compilation paper defining all the properties of the subclass (Hosseinzadeh et al. 2017). Professor Pat Kelly has long studied the properties of host galaxies of SNe. Dr. Saurabh W. Jha (Rutgers) and Dr. Mi Dai (Johns Hopkins) have expertise in identifying young supernova candidates to trigger HST in the SIRAH program. Professor Nathan Smith is an expert in the properties and evolution of massive stars, and on spectroscopy of SNe. Dr. Tamas Szalai is an expert in SN dust and infrared observations, which has proven to be an important aspect of some SNe Ibn (like SN 2006jc). Dr. Schuyler Van Dyk is an expert in HST photometry of SNe and in the study of stripped-envelope SNe. Dr. WeiKang Zheng is an expert at CCD imaging and photometry of SNe, both ground-based and HST; he will construct multifilter light curves of the object. Dr. Justin Pierel and Dr. Melissa Shahbandeh are postdocs at STScI, and Mr. Qinan Wang is a graduate student at STScI/JHU, working with PI Fox. All three are expert observers with extensive spectroscopic data reduction and analysis experience. Stellar Physics and Stellar Types 6 false true false false false false SUPPORTED EXT-STAR SUPERNOVA NO J2000 STIS/FUV-MAMA Spectroscopic No No G140L 1425 STIS/NUV-MAMA Spectroscopic No No G230L 2376 STIS/NUV-MAMA Spectroscopic No No G230L 2376 /Users/ofox/Work/proposals/JWST/GO4/Survey/OP-cache/survey_cycle4_phaseII_v2_25shi-v01.xml 1754400451398 Timing link suitability includes constraints ([02 After 01 by at most 1.1 days] [04 After 01 by 6.0 to 12.0 days]) The scheduling data was generated by CASM 33.1. CASM was run in Phase II mode. Likely to acquire on bright SN. (Tic-Visit :proposal-id 17814 :visit-id "01" :proposal-version -1 :trans-version "20250624" :date "05-Aug-2025 09:27:31.0" :trans-errors '(:WARNINGS 0 :ERRORS 0 :HEALTH-AND-SAFETY 0 :FATAL-ERRORS 0 :CONTINUABLE-FATALS 0) :number-of-orbits 1 :saa-model "24" :si-bright-earth-limb-angle 20.0 :data-volume 87408 :tdrss-contact-duration 0 :coron NIL ) (Tic-Obset :proposal-id 17814 :visit-id "01" :obset-id "01" :pcs-mode "FGS" ) (Tic-Orbit :proposal-id 17814 :visit-id "01" :orbit-number 1 :pcs-time 380 :si-vis-utilization 2603 :al-overhead-at-end 0 :internal-dur-at-end 394 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 2983 :pcs-gap 0 ) true 1 0 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. Used 10,000K Blackbody normalized to V=16. SN should be bright during initial acquisition. /Users/ofox/Work/proposals/JWST/GO4/Survey/OP-cache/survey_cycle4_phaseII_v2_25shi-v02.xml 1754400452136 Timing link suitability includes constraints ([02 After 01 by at most 1.1 days] [03 After 02 by at most 1.1 days]) The scheduling data was generated by CASM 33.1. CASM was run in Phase II mode. Likely to acquire on bright SN. (Tic-Visit :proposal-id 17814 :visit-id "02" :proposal-version -1 :trans-version "20250624" :date "05-Aug-2025 09:27:32.0" :trans-errors '(:WARNINGS 0 :ERRORS 0 :HEALTH-AND-SAFETY 0 :FATAL-ERRORS 0 :CONTINUABLE-FATALS 0) :number-of-orbits 1 :saa-model "24" :si-bright-earth-limb-angle 20.0 :data-volume 87408 :tdrss-contact-duration 0 :coron NIL ) (Tic-Obset :proposal-id 17814 :visit-id "02" :obset-id "02" :pcs-mode "FGS" ) (Tic-Orbit :proposal-id 17814 :visit-id "02" :orbit-number 1 :pcs-time 380 :si-vis-utilization 2603 :al-overhead-at-end 0 :internal-dur-at-end 394 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 2983 :pcs-gap 0 ) true 1 0 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. Used 10,000K Blackbody normalized to V=16. SN should be bright during initial acquisition. /Users/ofox/Work/proposals/JWST/GO4/Survey/OP-cache/survey_cycle4_phaseII_v2_25shi-v03.xml 1754400452664 Timing link suitability includes constraints ([03 After 02 by at most 1.1 days]) The scheduling data was generated by CASM 33.1. CASM was run in Phase II mode. Likely to acquire on bright SN. (Tic-Visit :proposal-id 17814 :visit-id "03" :proposal-version -1 :trans-version "20250624" :date "05-Aug-2025 09:27:32.0" :trans-errors '(:WARNINGS 0 :ERRORS 0 :HEALTH-AND-SAFETY 0 :FATAL-ERRORS 0 :CONTINUABLE-FATALS 0) :number-of-orbits 1 :saa-model "24" :si-bright-earth-limb-angle 20.0 :data-volume 87408 :tdrss-contact-duration 0 :coron NIL ) (Tic-Obset :proposal-id 17814 :visit-id "03" :obset-id "03" :pcs-mode "FGS" ) (Tic-Orbit :proposal-id 17814 :visit-id "03" :orbit-number 1 :pcs-time 380 :si-vis-utilization 2603 :al-overhead-at-end 0 :internal-dur-at-end 394 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 2983 :pcs-gap 0 ) true 1 0 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. Used 10,000K Blackbody normalized to V=16. SN should be bright during initial acquisition. 1754400453078 Timing link suitability includes constraints ([04 After 01 by 6.0 to 12.0 days] [05 After 04 by at most 0.1 days]) The scheduling data was generated by CASM 33.1. CASM was run in Phase II mode. /Users/ofox/Work/proposals/JWST/GO4/Survey/OP-cache/survey_cycle4_phaseII_v2_25shi-v04.xml Likely to acquire on bright SN. (Tic-Visit :proposal-id 17814 :visit-id "04" :proposal-version -1 :trans-version "20250624" :date "05-Aug-2025 09:27:33.0" :trans-errors '(:WARNINGS 0 :ERRORS 0 :HEALTH-AND-SAFETY 0 :FATAL-ERRORS 0 :CONTINUABLE-FATALS 0) :number-of-orbits 1 :saa-model "24" :si-bright-earth-limb-angle 20.0 :data-volume 87408 :tdrss-contact-duration 0 :coron NIL ) (Tic-Obset :proposal-id 17814 :visit-id "04" :obset-id "04" :pcs-mode "FGS" ) (Tic-Orbit :proposal-id 17814 :visit-id "04" :orbit-number 1 :pcs-time 380 :si-vis-utilization 2599 :al-overhead-at-end 0 :internal-dur-at-end 394 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 2983 :pcs-gap 0 ) true 1 0 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. Used 10,000K Blackbody normalized to V=16. SN should be bright during initial acquisition. Assuming a 7,000K Blackbody around 10 days post-max. 1754400453494 Timing link suitability includes constraints ([05 After 04 by at most 0.1 days] [06 After 05 by at most 0.1 days]) The scheduling data was generated by CASM 33.1. CASM was run in Phase II mode. /Users/ofox/Work/proposals/JWST/GO4/Survey/OP-cache/survey_cycle4_phaseII_v2_25shi-v05.xml Likely to acquire on bright SN. (Tic-Visit :proposal-id 17814 :visit-id "05" :proposal-version -1 :trans-version "20250624" :date "05-Aug-2025 09:27:33.0" :trans-errors '(:WARNINGS 0 :ERRORS 0 :HEALTH-AND-SAFETY 0 :FATAL-ERRORS 0 :CONTINUABLE-FATALS 0) :number-of-orbits 1 :saa-model "24" :si-bright-earth-limb-angle 20.0 :data-volume 87408 :tdrss-contact-duration 0 :coron NIL ) (Tic-Obset :proposal-id 17814 :visit-id "05" :obset-id "05" :pcs-mode "FGS" ) (Tic-Orbit :proposal-id 17814 :visit-id "05" :orbit-number 1 :pcs-time 380 :si-vis-utilization 2599 :al-overhead-at-end 0 :internal-dur-at-end 394 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 2983 :pcs-gap 0 ) true 1 0 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. Used 10,000K Blackbody normalized to V=16. SN should be bright during initial acquisition. Assuming a 7,000K Blackbody around 10 days post-max. 1754400454063 Timing link suitability includes constraints ([06 After 05 by at most 0.1 days]) The scheduling data was generated by CASM 33.1. CASM was run in Phase II mode. /Users/ofox/Work/proposals/JWST/GO4/Survey/OP-cache/survey_cycle4_phaseII_v2_25shi-v06.xml Likely to acquire on bright SN. (Tic-Visit :proposal-id 17814 :visit-id "06" :proposal-version -1 :trans-version "20250624" :date "05-Aug-2025 09:27:34.0" :trans-errors '(:WARNINGS 0 :ERRORS 0 :HEALTH-AND-SAFETY 0 :FATAL-ERRORS 0 :CONTINUABLE-FATALS 0) :number-of-orbits 1 :saa-model "24" :si-bright-earth-limb-angle 20.0 :data-volume 87408 :tdrss-contact-duration 0 :coron NIL ) (Tic-Obset :proposal-id 17814 :visit-id "06" :obset-id "06" :pcs-mode "FGS" ) (Tic-Orbit :proposal-id 17814 :visit-id "06" :orbit-number 1 :pcs-time 380 :si-vis-utilization 2599 :al-overhead-at-end 0 :internal-dur-at-end 394 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 2983 :pcs-gap 0 ) true 1 0 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. Used 10,000K Blackbody normalized to V=16. SN should be bright during initial acquisition. Assuming a 7,000K Blackbody around 10 days post-max.