0 Assigned ID: 2591 ----- Attempting Submission 1 (Thu Sep 30 12:38:19 GMT 2021) ----- Submission 1 of phase II for 16874. 1 visit/2 orbtits for supernova 2021qvr observed with WFC3/UVIS imaging in F275W, F336W, F555W. -1718544364 ----- Attempting Submission 1 (Wed Dec 01 16:26:20 GMT 2021) ----- Ultra-rapid or "flash" spectroscopy of young core-collapse supernovae enables the detection of narrow emission lines that arise from shock ionization of local circumstellar material (CSM). This CSM is a direct tracer of progenitor star surface abundance in the last years before explosion and mass-loss history. A completely independent method for establishing progenitor properties is through direct detection of a source in deep pre-explosion imaging. SN 2021qvr is an extremely rare type II-L supernova with both flash spectra and progenitor candidates in pre-explosion imaging. However, to fully leverage these data, we need high-resolution follow up imaging to isolate the progenitor candidate in pre-explosion HST frames. In addition, ultraviolet follow-up imaging would enable us to understand its late-time bolometric behavior and to constrain the CSM mass ejected decades before core collapse, establishing how the progenitor star evolved and what its mass-loss rate was in the final years before explosion. We will observe the site of supernova (SN) 2021qvr during Cycle 29 with the Wide Field Camera 3 UV/visible detecting CCD in F275W, F336W, and F555W. We expect the SN to be 24-26 mag in the UV bands at the time it is observed and around 20-22 mag in F555W. Our goal is to obtain deep imaging of SN2021qvr and the surrounding field in the two UV filters while maximizing the signal-to-noise. We will therefore use 1 orbit in F275W and 2/3 orbit in F336W. We expect to achieve S/N>10 on SN2021qvr in both frames given our setup and exposure times. The remaining 1/3 orbit in F555W is designed to overlap with pre-explosion UVIS imaging in the same filter in order to perform astrometric alignment between the two images. The technical goal is therefore to detect as many point sources as possible that overlap with the pre-explosion frames. We expect to observe sources down to F555W = 25.5 mag at S/N>10, which should result in hundreds of astrometric calibrators to achieve our goal of <=0.01 arcsec alignment precision. Dr. Kilpatrick is an expert in supernova follow up, supernova progenitor star studies, and analysis of HST imaging. He has written 5 papers in the past 4 years on supernovae with pre-explosion HST imaging that constrained the properties of their progenitor stars. He has also written a public, open-source pipeline for analysis of HST imaging, which has been used in analysis for 5 refereed publications in the past 2 years. Mr. Jacobson-Galan has written 5 publications on exotic, nearby supernovae over the past 3 years, including publications that focus on the progenitor stars of Calcium-rich and thermonuclear supernovae. Dr. Samaporn Tinyanont is an expert in core-collapse supernova observations and the connection between massive stars and their terminal explosions. He recently published a progenitor mass measurement of SN 2020fqv using light curve properties, nebular spectroscopy, and pre-explosion HST imaging limit. Stellar Physics and Stellar Types Stellar Populations and the Interstellar Medium 3 false false true false false false true false SUPPORTED STAR SUPERNOVA SUPERNOVA TYPE II J2000 J2000 WFC3/UVIS Imaging No No F275W WFC3/UVIS Imaging No No F336W WFC3/UVIS Imaging No No F555W POS-TARG DITHER 0.145 LINE false false 2 46.84 WFC3-UVIS-DITHER-LINE 1 false POS-TARG DITHER 0.173 LINE 0.112 false false 81.785 4 23.884 WFC3-UVIS-DITHER-BOX 2 false 1638375858600 /private/var/folders/_s/tc8h43192s58wb4s6m2lbfcw0000gn/T/OPVisit2872032390560652020.xml The scheduling data was generated by CASM 29.2. CASM was run in Phase II mode. (Tic-Visit :proposal-id 16874 :visit-id "01" :proposal-version -1 :trans-version "20210514" :date "01-Dec-2021 10:24:18.0" :trans-errors '(:WARNINGS 0 :ERRORS 0 :HEALTH-AND-SAFETY 0 :FATAL-ERRORS 0 :CONTINUABLE-FATALS 0) :number-of-orbits 2 :saa-model "29" :si-bright-earth-limb-angle 20.0 :data-volume 2309984 :tdrss-contact-duration 0 :coron NIL ) (Tic-Obset :proposal-id 16874 :visit-id "01" :obset-id "01" :pcs-mode "FGS" ) (Tic-Orbit :proposal-id 16874 :visit-id "01" :orbit-number 1 :pcs-time 383 :si-vis-utilization 2771 :al-overhead-at-end 125 :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 16874 :visit-id "01" :orbit-number 2 :pcs-time 392 :si-vis-utilization 2762 :al-overhead-at-end 123 :internal-dur-at-end 668 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 3157 :pcs-gap 0 ) true 2 0