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: 3535 ----- Attempting Submission 1 (Fri Mar 25 20:50:41 GMT 2022) ----- HST Phase I Proposal 3535 successfully submitted. Receipt: # 3535-1 ----- Attempting Submission 2 (Fri Mar 25 23:55:00 GMT 2022) ----- ToO doesn't require Orbit Planner. This pattern is not used in this proposal. Re-optimized orbits. Forgot. 616615965 ----- Attempting Submission 1 (Thu Jul 14 13:49:13 GMT 2022) ----- ----- Attempting Submission 2 (Fri Apr 07 10:47:28 GMT 2023) ----- ----- Attempting Submission 4 (Fri Sep 29 19:32:39 GMT 2023) ----- HST Phase II Proposal 17195 successfully submitted. Receipt: # 17195-4 ----- Attempting Submission 5 (Fri Sep 29 19:37:41 GMT 2023) ----- Keeping dither pattern handy just in case. 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, 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. 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. 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 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. 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. Jose Groh is an expert at modeling SN shock interaction, particularly with CMFGEN, which we are proposing to use in this proposal. He has done similar work before (Groh et al. 2014, Boian & Groh, 2019), and will now implement the same analysis on SNe Ibn. 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). Stellar Physics and Stellar Types 6 false false true false false false false false SUPPORTED 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 POS-TARG DITHER 0.264 LINE false true 2 90.0 STIS-ALONG-SLIT 1 false 1696020906008 /private/var/folders/w_/lrgrpxmn21l5cct7f1x383qw0002kw/T/OPVisit9356336140659827925.xml Timing link suitability includes constraints ([02 After 01 by at most 0.1 days] [04 After 01 by 6.0 to 12.0 days]) The scheduling data was generated by CASM 31.1. CASM was run in Phase II mode. Likely to acquire on bright SN. (Tic-Visit :proposal-id 17195 :visit-id "01" :proposal-version -1 :trans-version "20230626" :date "29-Sep-2023 16:55:05.0" :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 17195 :visit-id "01" :obset-id "01" :pcs-mode "FGS" ) (Tic-Orbit :proposal-id 17195 :visit-id "01" :orbit-number 1 :pcs-time 443 :si-vis-utilization 2693 :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 3136 :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. Assuming a 10,000K Blackbody around peak. 1696020906357 /private/var/folders/w_/lrgrpxmn21l5cct7f1x383qw0002kw/T/OPVisit179710239015241225.xml Timing link suitability includes constraints ([02 After 01 by at most 0.1 days] [03 After 02 by at most 0.1 days]) The scheduling data was generated by CASM 31.1. CASM was run in Phase II mode. Likely to acquire on bright SN. (Tic-Visit :proposal-id 17195 :visit-id "02" :proposal-version -1 :trans-version "20230626" :date "29-Sep-2023 16:55:06.0" :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 17195 :visit-id "02" :obset-id "02" :pcs-mode "FGS" ) (Tic-Orbit :proposal-id 17195 :visit-id "02" :orbit-number 1 :pcs-time 443 :si-vis-utilization 2693 :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 3136 :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. Assuming a 10,000K Blackbody around peak. 1696020906675 /private/var/folders/w_/lrgrpxmn21l5cct7f1x383qw0002kw/T/OPVisit5802028358165336691.xml Timing link suitability includes constraints ([03 After 02 by at most 0.1 days]) The scheduling data was generated by CASM 31.1. CASM was run in Phase II mode. Likely to acquire on bright SN. (Tic-Visit :proposal-id 17195 :visit-id "03" :proposal-version -1 :trans-version "20230626" :date "29-Sep-2023 16:55:06.0" :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 17195 :visit-id "03" :obset-id "03" :pcs-mode "FGS" ) (Tic-Orbit :proposal-id 17195 :visit-id "03" :orbit-number 1 :pcs-time 443 :si-vis-utilization 2693 :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 3136 :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. Assuming a 10,000K Blackbody around peak. 1696020906982 /private/var/folders/w_/lrgrpxmn21l5cct7f1x383qw0002kw/T/OPVisit11361120496370303139.xml 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 31.1. CASM was run in Phase II mode. Likely to acquire on bright SN. (Tic-Visit :proposal-id 17195 :visit-id "04" :proposal-version -1 :trans-version "20230626" :date "29-Sep-2023 16:55:06.0" :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 17195 :visit-id "04" :obset-id "04" :pcs-mode "FGS" ) (Tic-Orbit :proposal-id 17195 :visit-id "04" :orbit-number 1 :pcs-time 443 :si-vis-utilization 2693 :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 3136 :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. 1696020907284 /private/var/folders/w_/lrgrpxmn21l5cct7f1x383qw0002kw/T/OPVisit1771748392929296716.xml 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 31.1. CASM was run in Phase II mode. Likely to acquire on bright SN. (Tic-Visit :proposal-id 17195 :visit-id "05" :proposal-version -1 :trans-version "20230626" :date "29-Sep-2023 16:55:07.0" :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 17195 :visit-id "05" :obset-id "05" :pcs-mode "FGS" ) (Tic-Orbit :proposal-id 17195 :visit-id "05" :orbit-number 1 :pcs-time 443 :si-vis-utilization 2693 :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 3136 :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. 1696020907600 /private/var/folders/w_/lrgrpxmn21l5cct7f1x383qw0002kw/T/OPVisit2258783953764495683.xml Timing link suitability includes constraints ([06 After 05 by at most 0.1 days]) The scheduling data was generated by CASM 31.1. CASM was run in Phase II mode. Likely to acquire on bright SN. (Tic-Visit :proposal-id 17195 :visit-id "06" :proposal-version -1 :trans-version "20230626" :date "29-Sep-2023 16:55:07.0" :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 17195 :visit-id "06" :obset-id "06" :pcs-mode "FGS" ) (Tic-Orbit :proposal-id 17195 :visit-id "06" :orbit-number 1 :pcs-time 443 :si-vis-utilization 2693 :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 3136 :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.