0 Assigned ID: 121 ----- Attempting Submission 1 (Tue Mar 03 17:07:22 GMT 2020) ----- HST Phase I Proposal 121 successfully submitted. Receipt: # 121-1 ----- Attempting Submission 2 (Thu Mar 05 19:00:30 GMT 2020) ----- HST Phase I Proposal 121 successfully submitted. Receipt: # 121-2 ----- Attempting Submission 3 (Thu Mar 05 19:08:40 GMT 2020) ----- HST Phase I Proposal 121 successfully submitted. Receipt: # 121-3 ----- Attempting Submission 4 (Fri Mar 06 02:43:59 GMT 2020) ----- HST Phase I Proposal 121 successfully submitted. Receipt: # 121-4 ----- Attempting Submission 5 (Fri Mar 06 16:26:43 GMT 2020) ----- HST Phase I Proposal 121 successfully submitted. Receipt: # 121-5 ----- Attempting Submission 6 (Fri Mar 06 23:59:17 GMT 2020) ----- HST Phase I Proposal 121 successfully submitted. Receipt: # 121-6 This target is not used in this proposal. switched to STIS-CCD + G230LB + 52X0.2E1 with cr-split -1821199849 ----- Attempting Submission 1 (Fri Jun 26 22:32:41 GMT 2020) ----- HST Phase II Proposal 16178 successfully submitted. Receipt: # 16178-1 ----- Attempting Submission 2 (Fri Aug 20 23:00:34 GMT 2021) ----- HST Phase II Proposal 16178 successfully submitted. Receipt: # 16178-2 ----- Attempting Submission 4 (Fri Sep 10 19:10:36 GMT 2021) ----- HST Phase II Proposal 16178 successfully submitted. Receipt: # 16178-4 ----- Attempting Submission 5 (Fri Sep 10 20:42:39 GMT 2021) ----- HST Phase II Proposal 16178 successfully submitted. Receipt: # 16178-5 ----- Attempting Submission 6 (Sat Sep 11 00:04:45 GMT 2021) ----- See "Proposal Description". We propose to obtain a series of three early-time UV spectra of one stripped-envelope core-collapse supernova (either a normal SN Ib or a normal SN Ic), starting well before maximum brightness. The underlying nature of these objects, from the mass-loss process stripping the envelope to the details of the explosion mechanism, remain mysterious. Connections to gamma-ray bursts and X-ray flashes further motivate this study. Many high-redshift SNe are being found in deep transient surveys, but the ability to distinguish between thermonuclear Type Ia SNe and stripped-envelope core-collapse SNe requires thorough knowledge of the latter at UV wavelengths with a low-z object. By comparing the evolution of the spectra as the photosphere recedes to deeper layers of the ejecta with our time series of spectral models, we will gain a better understanding of the explosion mechanism and the degree of mixing during the explosion. Moreover, we should be able to determine the metal content of the progenitor's outer layers with our spectral models and compare with the measured metallicity of the environment. The heterogeneity seen in stripped-envelope SNe compels us to choose a normal SN Ib or SN Ic, objects with DIFFERENT characteristics than the ones that HST has observed in previous Cycles (SNe Ic-pec, IIb, Ibn), thereby gaining further insights into this unique class of cosmic explosion. We need to seize this opportunity now, while we have access to the space UV, and indeed the UV is an HST Cycle 28 priority. Obtain STIS UV spectra of one bright (Vmax < 15.5 mag), nearby, stripped-envelope SN as soon as possible after discovery (preferably at t < -7 d, relative to maximum brightness), with subsequent spectra taken at intervals of 5 days, for a total of 3 epochs (6 + 5 + 6 = 17 orbits total). The cadence of the spectral observations is determined from the timescale over which significant changes are observed in ground-based optical/near-UV spectra. -------- Realtime Justification -------- This is a disruptive ToO observation of a single bright SN. However, it is not an ultra-rapid (< 2 day turnaround) ToO. We will work with STScI staff to expedite the observations, and we will try to choose an object that minimizes the time between ToO activation and observations. If we trigger 13-14 days before maximum brightness, and we have a turnaround time of 4-7 days, the first observation will commence about 10-5 days before maximum light. We will use both the STIS/CCD and MAMA detectors to provide full wavelength coverage. The CCD observations can be done during the final MAMA orbit of each epoch. The spectra of SNe change on a timescale of 1-2 days at these early phases, so we prefer that the whole spectrum be obtained in a single visit. Although visits of 6 orbits using STIS/MAMA are discouraged owing to the interfering effects of the SAA, we hope that it will be possible, as it has been in previous cycles for this program. However, if this request cannot be accommodated in Cycle 28, we request visits not more than about 1 day from each other. We understand that in Cycle 28, we are strongly encouraged to structure our observations into visits of only 1-3 orbits duration each. As noted above, we prefer durations of up to 6 orbits (6, 5, and 6 for Visits 1, 2, and 3, respectively -- separated by about 5 days) because of the temporal variability of the supernova spectrum. However, we will be fine with restructuring our program to give a combination of 2-orbit or 3-orbit visits (3+3 = 6 and 3+2 = 5; 2+2+2 = 6 would be less desirable but still doable), if those shorter "subvisits" are within 1 day of teach other. There will be a loss of S/N at a given epoch, but we could still average the UV MAMA data from two reasonably closely spaced epochs. The optical CCD spectra take just 1 orbit (or a fraction of an orbit), so we would be able to use the optical spectra directly with the corresponding UV spectra, with no mixing of dates. We have considered the impact of reduced gyro operations on our program. They will not significantly impact this program. We will need to choose a target that has a suitable observing window in the immediate future (since this is a disruptive ToO). The orientation of the field is not relevant, nor is the spatial scan speed. ------ Calibration Justification ------- Our SN, which is optically bright, will have ground-based astrometry with respect to HST guide stars accurate to better than 0.2''. Using the STIS Acquisition ETC we find acquisition times of less than 1 min for all epochs, for the 0.2'' slit. Previously, we have successfully acquired SNe with STIS in this manner. --------- Additional Comments ---------- This is a ToO proposal. We will update our Phase 2 with the supernova coordinates as they become available. In order to make sure there are no bright objects in the target vicinity and to estimate the target UV flux, we will obtain rapid-response Swift/UVOT observations, as we have done in the past for this program. PI Alex Filippenko led the highly successful Lick Observatory Supernova Search for more than 2 decades, has been studying images and spectra of supernovae (SNe) for more than 3 decades, and has led numerous HST studies of nearby SNe (including HST UV spectral studies similar to the one proposed here). Schuyler Van Dyk is an expert in HST photometry of SNe and in the study of stripped-envelope SNe. Yi Yang and graduate student Kishore Patra (working under the direction of Filippenko) are experts in spectropolarimetry (complementary data that we plan to obtain with ground-based telescopes). Avishay Gal-Yam is the science lead of core-collapse SN studies with the 47 square degree, high-cadence (<1 day) Zwicky Transient Factory and is one of the primary sources of suitable targets. Assaf Horesh is in expert in radio observations of SNe and will provide complementary radio data. Paolo Mazzali is an expert at modeling the spectra of SNe through different depths in the ejecta; his models will be compared with the data. Sergiy Vasylyev is a graduate student at UC Berkeley who will work (under Filippenko's supervision) on the analysis of the HST and complementary spectra. Maryam Modjaz has long been a leader in determining the metallicities of the environments of core-collapse SNe through studies of HII regions, as well as in studying optical spectral sequences of SNe Ib/Ic. Graduate student Marc Williamson (working under the direction of Maryam Modjaz) has done important work on the classification and analysis of optical spectra of SNe~Ib/Ic. He is a main recent developer of the SN radiative transport code TARDIS and an experienced modeler of SNe~Ib/Ic. Tom Matheson is an expert in the spectroscopic properties of supernovae, especially stripped-envelope core-collapse SNe. Nathan Smith is an expert in the properties and evolution of massive stars, and on spectroscopy of SNe. Ori Fox studies dust, its formation in SN ejecta, and how it affects SN photometry, spectra, and interpretations. Tom Brink has much experience obtaining and reducing ground-based spectra, and complementary data of this type will be obtained for the program. 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. The above investigators have fruitfully worked together in the past and have many joint HST papers. Overall, members of the team have published more than 100 papers based at least in part on HST data. They have previously conducted studies of HST UV spectra of stripped-envelope SNe (specifically SNe Ic-pec, IIb, and Ibn). Stellar Physics and Stellar Types 6 false false true false false false false false SUPPORTED EXT-STAR SUPERNOVA NO J2000 EXT-STAR SUPERNOVA Pending identification of a type Ib or Ic supernova identified well before maximum brightness. A young stripped-envelope core collapse supernova with Vmax<15.5 mag STIS/NUV-MAMA Spectroscopic No No G230L 2376 STIS/CCD Spectroscopic No No G430L 4300 STIS/CCD Spectroscopic No No G750L 7751 STIS/NUV-MAMA Spectroscopic No No G230L 2376 STIS/CCD Spectroscopic No No G430L 4300 STIS/CCD Spectroscopic No No G750L 7751 STIS/NUV-MAMA Spectroscopic No No G230L 2376 STIS/CCD Spectroscopic No No G430L 4300 STIS/CCD Spectroscopic No No G750L 7751 1631317872439 /private/var/folders/p6/q91k3xz15c57tvm1j90zmd_00000gn/T/OPVisit17012484311639524626.xml The scheduling data was generated by CASM 29.2. CASM was run in Phase II mode. (Tic-Visit :proposal-id 16178 :visit-id "01" :proposal-version -1 :trans-version "20210514" :date "10-Sep-2021 19:51:11.0" :trans-errors '(:WARNINGS 0 :ERRORS 0 :HEALTH-AND-SAFETY 0 :FATAL-ERRORS 0 :CONTINUABLE-FATALS 0) :number-of-orbits 6 :saa-model "24" :si-bright-earth-limb-angle 20.0 :data-volume 846992 :tdrss-contact-duration 0 :coron NIL ) (Tic-Obset :proposal-id 16178 :visit-id "01" :obset-id "01" :pcs-mode "FGS" ) (Tic-Orbit :proposal-id 16178 :visit-id "01" :orbit-number 1 :pcs-time 393 :si-vis-utilization 2688 :al-overhead-at-end 0 :internal-dur-at-end 0 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 3157 :pcs-gap 0 ) (Tic-Orbit :proposal-id 16178 :visit-id "01" :orbit-number 2 :pcs-time 392 :si-vis-utilization 2688 :al-overhead-at-end 0 :internal-dur-at-end 0 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 3157 :pcs-gap 0 ) (Tic-Orbit :proposal-id 16178 :visit-id "01" :orbit-number 3 :pcs-time 392 :si-vis-utilization 2691 :al-overhead-at-end 0 :internal-dur-at-end 0 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 3157 :pcs-gap 0 ) (Tic-Orbit :proposal-id 16178 :visit-id "01" :orbit-number 4 :pcs-time 392 :si-vis-utilization 2689 :al-overhead-at-end 0 :internal-dur-at-end 0 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 3157 :pcs-gap 0 ) (Tic-Orbit :proposal-id 16178 :visit-id "01" :orbit-number 5 :pcs-time 392 :si-vis-utilization 2688 :al-overhead-at-end 0 :internal-dur-at-end 0 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 3157 :pcs-gap 0 ) (Tic-Orbit :proposal-id 16178 :visit-id "01" :orbit-number 6 :pcs-time 392 :si-vis-utilization 2690 :al-overhead-at-end 0 :internal-dur-at-end 660 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 3157 :pcs-gap 0 ) true 6 0 Target of Opportunity Our SN, though UV-faint, will be optically bright. Using the STIS Acquisition ETC and the spectrum of PTF12gzk obtained in Cycle 20, we find that a 2s exposure yields a S/N > 100. 1631318024920 /private/var/folders/p6/q91k3xz15c57tvm1j90zmd_00000gn/T/OPVisit17052246020226462940.xml The scheduling data was generated by CASM 29.2. CASM was run in Phase II mode. (Tic-Visit :proposal-id 16178 :visit-id "02" :proposal-version -1 :trans-version "20210514" :date "10-Sep-2021 19:53:44.0" :trans-errors '(:WARNINGS 0 :ERRORS 0 :HEALTH-AND-SAFETY 0 :FATAL-ERRORS 0 :CONTINUABLE-FATALS 0) :number-of-orbits 5 :saa-model "24" :si-bright-earth-limb-angle 20.0 :data-volume 718176 :tdrss-contact-duration 0 :coron NIL ) (Tic-Obset :proposal-id 16178 :visit-id "02" :obset-id "02" :pcs-mode "FGS" ) (Tic-Orbit :proposal-id 16178 :visit-id "02" :orbit-number 1 :pcs-time 393 :si-vis-utilization 2688 :al-overhead-at-end 0 :internal-dur-at-end 0 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 3157 :pcs-gap 0 ) (Tic-Orbit :proposal-id 16178 :visit-id "02" :orbit-number 2 :pcs-time 392 :si-vis-utilization 2688 :al-overhead-at-end 0 :internal-dur-at-end 0 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 3157 :pcs-gap 0 ) (Tic-Orbit :proposal-id 16178 :visit-id "02" :orbit-number 3 :pcs-time 392 :si-vis-utilization 2691 :al-overhead-at-end 0 :internal-dur-at-end 0 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 3157 :pcs-gap 0 ) (Tic-Orbit :proposal-id 16178 :visit-id "02" :orbit-number 4 :pcs-time 392 :si-vis-utilization 2689 :al-overhead-at-end 0 :internal-dur-at-end 0 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 3157 :pcs-gap 0 ) (Tic-Orbit :proposal-id 16178 :visit-id "02" :orbit-number 5 :pcs-time 392 :si-vis-utilization 2690 :al-overhead-at-end 0 :internal-dur-at-end 660 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 3157 :pcs-gap 0 ) true 5 0 Target of Opportunity Our SN, though UV-faint, will be optically bright. Using the STIS Acquisition ETC and the spectrum of PTF12gzk obtained in Cycle 20, we find that a 2s exposure yields a S/N > 100. 1631317986763 /private/var/folders/p6/q91k3xz15c57tvm1j90zmd_00000gn/T/OPVisit15139331064947883453.xml The scheduling data was generated by CASM 29.2. CASM was run in Phase II mode. (Tic-Visit :proposal-id 16178 :visit-id "03" :proposal-version -1 :trans-version "20210514" :date "10-Sep-2021 19:53:05.0" :trans-errors '(:WARNINGS 0 :ERRORS 0 :HEALTH-AND-SAFETY 0 :FATAL-ERRORS 0 :CONTINUABLE-FATALS 0) :number-of-orbits 6 :saa-model "24" :si-bright-earth-limb-angle 20.0 :data-volume 846992 :tdrss-contact-duration 0 :coron NIL ) (Tic-Obset :proposal-id 16178 :visit-id "03" :obset-id "03" :pcs-mode "FGS" ) (Tic-Orbit :proposal-id 16178 :visit-id "03" :orbit-number 1 :pcs-time 393 :si-vis-utilization 2688 :al-overhead-at-end 0 :internal-dur-at-end 0 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 3157 :pcs-gap 0 ) (Tic-Orbit :proposal-id 16178 :visit-id "03" :orbit-number 2 :pcs-time 392 :si-vis-utilization 2688 :al-overhead-at-end 0 :internal-dur-at-end 0 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 3157 :pcs-gap 0 ) (Tic-Orbit :proposal-id 16178 :visit-id "03" :orbit-number 3 :pcs-time 392 :si-vis-utilization 2691 :al-overhead-at-end 0 :internal-dur-at-end 0 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 3157 :pcs-gap 0 ) (Tic-Orbit :proposal-id 16178 :visit-id "03" :orbit-number 4 :pcs-time 392 :si-vis-utilization 2689 :al-overhead-at-end 0 :internal-dur-at-end 0 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 3157 :pcs-gap 0 ) (Tic-Orbit :proposal-id 16178 :visit-id "03" :orbit-number 5 :pcs-time 392 :si-vis-utilization 2688 :al-overhead-at-end 0 :internal-dur-at-end 0 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 3157 :pcs-gap 0 ) (Tic-Orbit :proposal-id 16178 :visit-id "03" :orbit-number 6 :pcs-time 392 :si-vis-utilization 2690 :al-overhead-at-end 0 :internal-dur-at-end 660 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 3157 :pcs-gap 0 ) true 6 0 Target of Opportunity Our SN, though UV-faint, will be optically bright. Using the STIS Acquisition ETC and the spectrum of PTF12gzk obtained in Cycle 20, we find that a 2s exposure yields a S/N > 100.