minor corrections -326567702 Assigned ID: 100 ----- Attempting Submission 1 (Tue Apr 04 16:03:40 GMT 2017) ----- HST Phase I Proposal 100 (failed.apt) successfully submitted. Receipt: # 100-1 ----- Attempting Submission 2 (Thu Apr 06 15:58:16 GMT 2017) ----- HST Phase I Proposal 100 (failed.apt) successfully submitted. Receipt: # 100-2 ----- Attempting Submission 3 (Fri Apr 07 17:57:52 GMT 2017) ----- 0 Your proposal could not be saved. Submission aborted. ----- Attempting Submission 1 (Tue Jul 18 18:14:18 GMT 2017) ----- Confirming the Formation of a Black Hole There are good observational and theoretical reasons to believe that 10-30% of the core-collapses of massive stars lead to the formation of black holes without a supernova explosion. We have been carrying out the first observational search for such failed supernovae using the Large Binocular Telescope. From seven years of LBT survey data we have one good candidate, NGC6946-BH1. HST observations in 2015 found a possible near-IR counterpart to the candidate that is significantly less luminous than the progenitor. If the source is related to BH1, this could be either emission from late time accretion luminosity or obscuration of a surviving star by an expanding shell of dust too cool to be detected in our warm SST observations. New HST WFC3/IR observations of the source should find that the source is either fainter (late-time accretion) or brighter (obscured by an expanding shell). This is critical information to inform proposals for JWST observations to search for colder dust. The goal is to obtain two IR (F110W and F160W) WFC3 images of a candidate failed supernova, where a massive star has undergone core collapse to form a black hole without an external supernova explosion. The filters and exposure times are chosen to match our previous observations. Stellar Physics 6 false false false false false false SUPPORTED STAR ACCRETION DISK J2000 J2000 F110W 23.8 F160W 22.4 in cycle 23 WFC3/IR Imaging No No F110W WFC3/IR Imaging No No F160W POS-TARG DITHER 0.605 LINE false false 3 41.788 WFC3-IR-DITHER-LINE-3PT 1 false The scheduling data was generated by CASM 25.2. CASM was run in Phase II mode. /tmp/OPVisit3407815686833116083.xml (Tic-Visit :proposal-id 15311 :visit-id "01" :proposal-version -1 :trans-version "20170613" :date "18-Jul-2017 14:11:57.0" :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 1410112 :tdrss-contact-duration 0 :coron NIL ) (Tic-Obset :proposal-id 15311 :visit-id "01" :obset-id "01" :pcs-mode "FGS" ) (Tic-Orbit :proposal-id 15311 :visit-id "01" :orbit-number 1 :pcs-time 333 :si-vis-utilization 3103 :al-overhead-at-end 0 :internal-dur-at-end 519 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 3471 :pcs-gap 0 ) true 1 0