0 Assigned ID: 502 ----- Attempting Submission 1 (Fri Apr 10 15:04:12 GMT 2015) ----- modified following suggestions from Knox Long 1721717201 ----- Attempting Submission 1 (Wed Jul 08 19:25:30 GMT 2015) ----- ----- Attempting Submission 2 (Thu Aug 27 18:20:52 GMT 2015) ----- Confirming NGC6946 BH1 - A Black Hole Formed in a Failed Supernova 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 the first four years of the survey, we are left with one good candidate, NGC6946 BH1. Deep HST and SST observations are needed to better constrain the vanishing of this massive star than is possible from the ground. Confirmation of the formation of a black hole in a failed supernova would represent one of the most exciting results by HST both scientifically and for the public. The goal is to obtain two optical (F606W and F814W) and 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 optical filters are chosen to match the archival data available for the source prior to the event. For UVIS, observing filter 1 at all dither points followed by filter 2 at all dither points produced slightly higher total integration times than interleaving the filters. There are 50 unused seconds in visit 03 WFC3/IR for which there was no efficient filler given the quantization of the WFC3/IR observing modes. However, mixing the optical/IR filters in each orbit (where auto-adjust on the optical would fill the time) seems to consistently produce slightly less total integration time. There is not strong need to coordinate the HST and Spitzer observations. Any evolution should be slow enough at this point to remove the need for adding a constraint. RESOLVED STELLAR POPULATIONS 12 false false false false 0.75 SUPPORTED STAR ACCRETION DISK J2000 J2000 WFC3/UVIS Imaging No No F606W WFC3/UVIS Imaging No No F814W WFC3/IR Imaging No No F110W WFC3/IR Imaging No No F160W POS-TARG DITHER 0.135 LINE false false 3 46.84 WFC3-UVIS-DITHER-LINE-3PT 1 false POS-TARG DITHER 0.636 LINE false false 2 41.788 WFC3-IR-DITHER-LINE 2 false The scheduling data was generated by CASM 23.2. CASM was run in Phase II mode. /tmp/OPVisit23209162279858677.xml (Tic-Visit :proposal-id 14266 :visit-id "01" :proposal-version -1 :trans-version "20150609" :date "27-Aug-2015 14:19:53.0" :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 3194848 :tdrss-contact-duration 0 :coron NIL ) (Tic-Obset :proposal-id 14266 :visit-id "01" :obset-id "01" :pcs-mode "FGS" ) (Tic-Orbit :proposal-id 14266 :visit-id "01" :orbit-number 1 :pcs-time 333 :si-vis-utilization 3143 :al-overhead-at-end 119 :internal-dur-at-end 31 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 3478 :pcs-gap 0 ) (Tic-Orbit :proposal-id 14266 :visit-id "01" :orbit-number 2 :pcs-time 222 :si-vis-utilization 3222 :al-overhead-at-end 0 :internal-dur-at-end 443 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 3478 :pcs-gap 0 ) true 2 0