Initial submission 1446151624 Assigned ID: 5206 ----- Attempting Submission 1 (Mon Mar 25 17:48:40 GMT 2024) ----- ORBITAL VISIBILITY OVERRUN Submission #4 - updating target details with second ToO trigger 1351183001 ----- Attempting Submission 1 (Thu Jul 11 16:22:34 GMT 2024) ----- ----- Attempting Submission 2 (Mon Jul 15 16:37:02 GMT 2024) ----- ----- Attempting Submission 3 (Tue Jul 08 16:07:41 GMT 2025) ----- ----- Attempting Submission 4 (Tue Sep 16 18:59:12 GMT 2025) ----- Warning applies to already completed visit 1 Finding Supernova Progenitor Stars in HST and JWST Imaging Many open questions in supernova (SN) physics rely on the connection between SNe and their progenitor stars. HST and now JWST provide a vast imaging archive of galaxies in the local Universe in which individual supernova progenitor stars can be isolated soon after they explode. Each new such event is a rare and unique opportunity in which we can compare a supernova explosion to the mass, metallicity, and local environments of the star that exploded. In many cases however, it is only possible to isolate the supernova progenitor star with high-resolution imaging follow up where local astrometric calibrators can be used to precisely align the supernova position with <0.1 arcsec precision. When adaptive optics imaging is not possible due to a lack of available guide stars, HST is the best available resource to obtain such follow-up imaging of the supernova. We propose a target-of-opportunity program to obtain such imaging with HST for 2 nearby (<40 Mpc) supernova targets during Cycle 32 that have pre-explosion HST or JWST imaging and precisely isolate the progenitor systems of these stellar explosions. This is a target-of-opportunity proposal to observe up to 2 supernovae at <40 Mpc with pre-explosion HST and/or JWST imaging. The goal of the proposal is to obtain imaging at the site of each supernova in order to precisely align to the pre-explosion imaging and identify or rule out the presence of a counterpart in the pre-explosion data. We are requesting a 3 week minimum response time from the time of trigger in order to guarantee that we can calibrate our exposures to the expected brightness of the supernova at the time of observation and avoid either saturating or failing to detect the primary supernova target. Our fiducial observation setup assumes that we will observe the supernova around or slightly after maximum light, with a required brightness of >16.5 mag to avoid saturating this source, which would limit the astrometric precision in centroiding on the supernova. We therefore use 68s exposures in F555W and use the UVIS2-C1K1C-SUB readout mode to reduce overheads between individual exposures. As we are targeting sources in galaxies at <40 Mpc, we expect the field around the supernova to be crowded with astrometric calibrators, and so the smaller readout region will not limit our science case. We have also adjusted FLASH=15 to avoid CTE losses. To improve PSF sampling, we use 4 iterations of a WFC3-UVIS-DITHER-BOX pattern for a total of 16 individual exposures. PI Kilpatrick is an expert in analysis of analysis of supernova progenitor stars in HST and Spitzer imaging, including archival research, data analysis, and modeling. He has written 6 papers in the last 6 years on this topic. Co-I Foley is a transient observer with significant experience using ground- and space-based observatories. He has experience in analysis of resolved stellar populations, including supernova progenitor stars of all types. He has preferred access to telescopes at Lick and Keck observatory that will be used for some of the follow up described in this proposal, including adaptive optics imaging. Co-I Davis is an expert in optical/infrared core-collapse supernova follow up and studies of core-collapse supernovae with strong circumstellar interaction. Co-I Gagliano is an expert in characterization of core-collapse supernova progenitor stars, their host galaxies, and forward modeling of their light curves and spectral energy distributions. Co-I Jacobson-Galan is an expert in follow up of supernovae of all types, characterization of their circumstellar environments, and detailed modeling of their strong shock interactions. He has written several papers on this topic over the past few years. Co-I Taggart is an expert in follow up of nearby supernovae and their characterization in Hubble Space Telescope data. Co-I Vazquez is an expert in modeling of Type II supernovae and their progenitor stars and has written a paper on the nearby SN 2019mhm within the past year. Stellar Physics and Stellar Types Stellar Populations and the Interstellar Medium 6 false false false false false false SUPPORTED STAR SUPERNOVA J2000 STAR SUPERNOVA NO J2000 WFC3/UVIS Imaging No No F555W WFC3/UVIS Imaging No No F555W POS-TARG DITHER 0.173 LINE 0.112 false false 81.785 4 23.884 WFC3-UVIS-DITHER-BOX 1 false The scheduling data was generated by CASM 33.1. CASM was run in Phase II mode. /private/var/folders/_s/tc8h43192s58wb4s6m2lbfcw0000gn/T/OPVisit8935966999523371510.xml 1753924033000 247.61281988414243 (Tic-Visit :proposal-id 17706 :visit-id "01" :proposal-version -1 :trans-version "20250624" :date "16-Sep-2025 13:58:10.0" :trans-errors '(:WARNINGS 1 :ERRORS 0 :HEALTH-AND-SAFETY 0 :FATAL-ERRORS 0 :CONTINUABLE-FATALS 0) :number-of-orbits 1 :saa-model "29" :si-bright-earth-limb-angle 20.0 :data-volume 285200 :tdrss-contact-duration 0 :coron NIL ) (Tic-Obset :proposal-id 17706 :visit-id "01" :obset-id "01" :pcs-mode "FGS" ) (Tic-Orbit :proposal-id 17706 :visit-id "01" :orbit-number 1 :pcs-time 380 :si-vis-utilization 2613 :al-overhead-at-end 85 :internal-dur-at-end 348 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 2979 :pcs-gap 0 ) true 1 1 Target of Opportunity Requirement is 21-60 days from initial trigger The scheduling data was generated by CASM 33.1. CASM was run in Phase II mode. /Users/ckilpatrick/Dropbox/Proposals/HST/cycle32/progenitor-TOO/OP-cache/progenitor-too_2-v02.xml (Tic-Visit :proposal-id 17706 :visit-id "02" :proposal-version -1 :trans-version "20250624" :date "16-Sep-2025 13:57:17.0" :trans-errors '(:WARNINGS 0 :ERRORS 0 :HEALTH-AND-SAFETY 0 :FATAL-ERRORS 0 :CONTINUABLE-FATALS 0) :number-of-orbits 1 :saa-model "29" :si-bright-earth-limb-angle 20.0 :data-volume 285200 :tdrss-contact-duration 0 :coron NIL ) (Tic-Obset :proposal-id 17706 :visit-id "02" :obset-id "02" :pcs-mode "FGS" ) (Tic-Orbit :proposal-id 17706 :visit-id "02" :orbit-number 1 :pcs-time 380 :si-vis-utilization 2613 :al-overhead-at-end 85 :internal-dur-at-end 348 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 3001 :pcs-gap 0 ) true 1 0 Target of Opportunity Requirement is 21-60 days from initial trigger