0 Assigned ID: 1328 ----- Attempting Submission 1 (Sun Jan 24 20:45:21 GMT 2021) ----- HST Phase I Proposal 1328 successfully submitted. Receipt: # 1328-1 ----- Attempting Submission 2 (Fri Jan 29 21:46:19 GMT 2021) ----- The number of orbits used exceeds the number allocated This pattern is not used in this proposal. Resubmission for repeat (54) of failed orbit (04). Left example orbit (56), but this should not be scheduled. -371242242 ----- Attempting Submission 1 (Thu Mar 25 15:47:20 GMT 2021) ----- ----- Attempting Submission 2 (Fri May 14 21:18:28 GMT 2021) ----- Orbit 56 should not be scheduled, this was just an example. Orbit 54 is a repeat submission for orbit 4, which failed. The dither pattern was used as an example but is not used in the actual visit. Confirming a Failed Supernova Candidate in M51 We request three orbits of ACS (F606W, F814W) and WFC3 IR (F110W, F160W) imaging at the location of a red supergiant star in M51 that has vanished, potentially as a 'failed supernova' that directly collapsed into a black hole. There is mounting evidence, both observational and theoretical, that 10-30% of core collapses do not yield a supernova explosion, but only one viable candidate for such a 'failed supernova' event has been observed thus far. Here, we have discovered a new, strong candidate for the disappearance of a luminous star in M51 which has been detected dozens of times with HST through late 2017. The star had the characteristics of a 25-30 M_sun red supergiant before it faded from view (>2.0 mag) in 2019 in a crowded region of a spiral arm. Deep HST multi-band imaging in the next few months will confirm the nature of the vanished star and rule out possible alternatives, such as a dust-obscured star. These observations will also constrain any fading remnant emission that may be associated with fallback accretion or an associated dust shell; depending on the results, this will be a prime target for further HST and JWST monitoring in future cycles. HST is the only currently available facility with the resolution and sensitivity, especially in the near-IR, necessary to perform this test. Confirmation of a second strong case for a 'failed supernova' will have broad consequences, not only for verifying this channel of stellar death, but for our understanding of stellar remnants, chemical enrichment, and ultimately models of black hole formation. Our primary science goal is to determine the nature of the fading source M51-DS1. To accomplish this we require three orbits total to observe in the optical (F606W, F814W) and near-infrared (F110W, F160W). The optical data (two orbits) will be with ACS/WFC, and the near-infrared (one orbit) with WFC3/IR. We split up our observations into three separate visits of one orbit each. For both the ACS and WFC3 observations, we use a standard four-point dither box for each orbit, with sub-pixel dithers in order to get closer to the native resolution of ACS. J. Jencson is an expert in core collapse supernovae and intermediate luminosity transients, with experience using HST imaging to constrain supernova progenitor systems. He is a postdoc running the 'Failed Supernova' HST search program, which is the dataset that identified the 'failed SN' that is the subject of this DD request. D. Sand is the PI of the HST 'Failed Supernova' program . He has extensive experience with HST and observations of supernovae and their environments. J. Strader is an expert in HST data reduction and analyses, along with generic time series analysis. One focus of his research is on the compact remnants (i.e. neutron stars and black holes) that result from massive star death. N. Smith is a world expert in massive star evolution and observations, and will provide help in the interpretation of the disappearing star in our program. J. Andrews has HST imaging expertise, and has been PI of several programs. Her research focuses on characterizing the progenitors of core collapse supernovae, specifically focusing on their mass-loss history via CSM interaction. S. Valenti has worked extensively on core collapse supernovae and other transients; he is skilled at interpreting observations to infer the mass and properties of the progenitor star. J. Pearson is a new first year graduate student who will cut her teeth on this program. Stellar Physics and Stellar Types 3 false false false false false false false SUPPORTED STAR CIRCUMSTELLAR MATTER SUPERGIANT O J2000 J2000 ACS/WFC Imaging No No F606W ACS/WFC Imaging No No F814W WFC3/IR Imaging No No F110W WFC3/IR Imaging No No F160W POS-TARG DITHER 0.262 LINE 0.192 false false 68.14 4 18.39 ACS-WFC-DITHER-BOX 1 false POS-TARG DITHER 0.605 LINE false false 3 41.788 WFC3-IR-DITHER-LINE-3PT 2 false POS-TARG DITHER 0.572 LINE 0.365 false false 74.653 4 18.528 WFC3-IR-DITHER-BOX-MIN 3 false The scheduling data was generated by CASM 29.0. CASM was run in Phase II mode. 1619642125000 163.7015127807801 (Tic-Visit :proposal-id 16508 :visit-id "01" :proposal-version -1 :trans-version "20200619" :date "14-May-2021 14:16:28.0" :trans-errors '(:WARNINGS 0 :ERRORS 0 :HEALTH-AND-SAFETY 0 :FATAL-ERRORS 0 :CONTINUABLE-FATALS 0) :number-of-orbits 1 :saa-model "27" :si-bright-earth-limb-angle 20.0 :data-volume 1136896 :tdrss-contact-duration 0 :coron NIL ) (Tic-Obset :proposal-id 16508 :visit-id "01" :obset-id "01" :pcs-mode "FGS" ) (Tic-Orbit :proposal-id 16508 :visit-id "01" :orbit-number 1 :pcs-time 383 :si-vis-utilization 2902 :al-overhead-at-end 0 :internal-dur-at-end 347 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 3285 :pcs-gap 0 ) true 1 0 The scheduling data was generated by CASM 29.0. CASM was run in Phase II mode. 1619699289000 163.7015127807801 (Tic-Visit :proposal-id 16508 :visit-id "02" :proposal-version -1 :trans-version "20200619" :date "14-May-2021 14:16:29.0" :trans-errors '(:WARNINGS 0 :ERRORS 0 :HEALTH-AND-SAFETY 0 :FATAL-ERRORS 0 :CONTINUABLE-FATALS 0) :number-of-orbits 1 :saa-model "27" :si-bright-earth-limb-angle 20.0 :data-volume 1136896 :tdrss-contact-duration 0 :coron NIL ) (Tic-Obset :proposal-id 16508 :visit-id "02" :obset-id "02" :pcs-mode "FGS" ) (Tic-Orbit :proposal-id 16508 :visit-id "02" :orbit-number 1 :pcs-time 383 :si-vis-utilization 2902 :al-overhead-at-end 0 :internal-dur-at-end 347 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 3285 :pcs-gap 0 ) true 1 0 The scheduling data was generated by CASM 29.0. CASM was run in Phase II mode. 1619941408000 144.0 (Tic-Visit :proposal-id 16508 :visit-id "04" :proposal-version -1 :trans-version "20200619" :date "14-May-2021 14:16:30.0" :trans-errors '(:WARNINGS 0 :ERRORS 0 :HEALTH-AND-SAFETY 0 :FATAL-ERRORS 0 :CONTINUABLE-FATALS 0) :number-of-orbits 1 :saa-model "30" :si-bright-earth-limb-angle 20.0 :data-volume 1392720 :tdrss-contact-duration 0 :coron NIL ) (Tic-Obset :proposal-id 16508 :visit-id "04" :obset-id "04" :pcs-mode "FGS" ) (Tic-Orbit :proposal-id 16508 :visit-id "04" :orbit-number 1 :pcs-time 383 :si-vis-utilization 2868 :al-overhead-at-end 0 :internal-dur-at-end 652 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 3285 :pcs-gap 0 ) true 1 0 The scheduling data was generated by CASM 29.0. CASM was run in Phase II mode. HOPR repeat of visit 04 (Tic-Visit :proposal-id 16508 :visit-id "54" :proposal-version -1 :trans-version "20200619" :date "14-May-2021 10:28:51.0" :trans-errors '(:WARNINGS 0 :ERRORS 0 :HEALTH-AND-SAFETY 0 :FATAL-ERRORS 0 :CONTINUABLE-FATALS 0) :number-of-orbits 1 :saa-model "30" :si-bright-earth-limb-angle 20.0 :data-volume 1392720 :tdrss-contact-duration 0 :coron NIL ) (Tic-Obset :proposal-id 16508 :visit-id "54" :obset-id "54" :pcs-mode "FGS" ) (Tic-Orbit :proposal-id 16508 :visit-id "54" :orbit-number 1 :pcs-time 383 :si-vis-utilization 2868 :al-overhead-at-end 0 :internal-dur-at-end 652 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 3285 :pcs-gap 0 ) true 1 0