0 Assigned ID: 1130 ----- Attempting Submission 1 (Fri Apr 07 23:34:58 GMT 2017) ----- 0 ----- Attempting Submission 1 (Thu Jul 20 01:02:46 GMT 2017) ----- The Progenitor of Supernova 2016gkg Supernova (SN) 2016gkg is called to be one of the most interesting events of its kind in the coming years. Its discovery minutes/hours after explosion, subsequent intensive monitoring from ground and space, and the existence of pre-explosion HST imaging where a progenitor candidate was detected, makes this SN an ideal case to study the fate of massive stars that explode after losing most of their outer envelopes. We propose to revisit the SN site with HST once the ejecta fade below the pre-explosion brightness in order to test the progenitor identification. This will also allow a better characterization of the progenitor object, which is crucial to confirm our proposal that it belonged to an interacting binary system. The images will have additional archival value as they will sample a large fraction of the host galaxy NGC 613. We will re-observe the site of SN 2016gkg in NGC 613 using ACS/WFC through three optical bands that most closely resemble the available pre-SN observations (i.e., F435W, F606W, and F814W) in order to determine whether the progenitor candidate has disappeared. According to our modeling, the candidate object is indeed the SN progenitor, so we expect the observed flux to be below the pre-explosion level in all bands. We expect the fading SN ejecta to be at 26 <F435W< 27 mag; 25.5 <F606W< 26.5 mag; and 25.5 <F814W< 26.5 mag at the time of our observations. In order to increase the potential archival value of the images, we decided to center the FOV near the galaxy nucleus, and NOT AT THE SN LOCATION. Nevertheless, the SN site sits comfortably in one of the WFC chips. Our program comprises one visit containing two orbits. We will divide the time among the three requested bands, obtaining total exposure times of 1600 s in F435W, 1370 s in F606W, and 1800 s in F814W. For each filter we will subdivide the exposures into two dithered images. According to the ACS ETC, with those exposure times, we will reach F435W~ 27.8 mag, F606W~ 27.9 mag, and F814W~ 27.1 mag, with a signal-to-noise ratio of S/N ~ 3. In order to allow enough time for the SN to fade below the flux of the pre-SN object we have placed a scheduling constraint for the observations after July 3, 2018 (according to the observability windows allowed by the "Visit Planner" tool). This means that our program can be scheduled at the end of Cycle 25, or during Cycle 26. We have checked for bright nearby sources and found that only one such source (a ~10th mag field star) is bright enough to saturate. However, its location is outside the chip FOV. We have also found that there is no need for post-flash exposures in any of the bands because the exposure times are long enough to avoid CTE problems. Stellar Physics 6 false false false false false false SUPPORTED EXT-STAR SUPERNOVA Given coordinates are not those of the SN because we chose to center the FOV near the host-galaxy nucleus. J2000 J2000 ACS/WFC Imaging No No F435W ACS/WFC Imaging No No F606W ACS/WFC Imaging No No F814W POS-TARG DITHER 3.034 LINE false false 2 85.29 ACS-WFC-DITHER-LINE 1 false /media/gaston/HD-PNTU3/trabajo/observacion/propuestas/hst_cycle25/sn2016gkg/phase2/OP-cache/sn2016gkg-v01.xml The scheduling data was generated by CASM 25.2. CASM was run in Phase II mode. This visit contains the whole program. Two orbits that will be used to observe with ACS/WFC and filters F435W, F606W, and F814W. (Tic-Visit :proposal-id 15272 :visit-id "01" :proposal-version -1 :trans-version "20170613" :date "19-Jul-2017 21:56:19.0" :trans-errors '(:WARNINGS 0 :ERRORS 0 :HEALTH-AND-SAFETY 0 :FATAL-ERRORS 0 :CONTINUABLE-FATALS 0) :number-of-orbits 2 :saa-model "27" :si-bright-earth-limb-angle 20.0 :data-volume 1705344 :tdrss-contact-duration 0 :coron NIL ) (Tic-Obset :proposal-id 15272 :visit-id "01" :obset-id "01" :pcs-mode "FGS" ) (Tic-Orbit :proposal-id 15272 :visit-id "01" :orbit-number 1 :pcs-time 333 :si-vis-utilization 2892 :al-overhead-at-end 0 :internal-dur-at-end 0 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 3225 :pcs-gap 0 ) (Tic-Orbit :proposal-id 15272 :visit-id "01" :orbit-number 2 :pcs-time 222 :si-vis-utilization 3002 :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 3225 :pcs-gap 0 ) true 2 0