0 Assigned ID: 687 ----- Attempting Submission 1 (Thu Jan 31 00:18:44 GMT 2019) ----- HST Phase I Proposal 687 (2017ein.apt) successfully submitted. Receipt: # 687-1 ----- Attempting Submission 2 (Thu Jan 31 00:24:14 GMT 2019) ----- HST Phase I Proposal 687 (2017ein.apt) successfully submitted. Receipt: # 687-2 ----- Attempting Submission 3 (Thu Jan 31 00:46:50 GMT 2019) ----- 0 ----- Attempting Submission 1 (Sun Apr 07 19:10:39 GMT 2019) ----- HST Phase II Proposal 15691 (15691.apt) successfully submitted. Receipt: # 15691-1 ----- Attempting Submission 2 (Fri Apr 26 20:38:47 GMT 2019) ----- The Progenitor of Supernova 2017ein Supernova (SN) 2017ein is the first Type Ic supernova with a credible progenitor candidate. This unprecedented discovery has the potential to revolutionize the study of core-collapse SNe by directly tying a stripped-envelope SN to a progenitor system with well-measured properties. However, follow up is necessary to robustly test the association between SN 2017ein and its progenitor candidate. We propose to revisit the site of SN 2017ein with HST once the SN has faded below the pre-explosion brightness. This observation will provide an unambiguous test of the association between the SN and progenitor candidate and better characterization of its pre-explosion properties. These images will also have archival value by provide an additional epoch of optical imaging covering the host galaxy NGC 3938. We propose to observe the site of supernova 2017ein in cycle 26 with the Wide Field Camera 3 (WFC3) UV/visible (UVIS) detecting CCD in F555W and F814W. The filters were chosen to match pre-explosion imaging of the site of this supernova where a counterpart was detected in WFPC2 F555W and F814W imaging from 2005. Based on light curves of the supernova from 2017 and 2018, we expect the source to be 26 mag in F555W and F814W, which is fainter than the pre-explosion magnitudes of the counterpart. Due to the fact that the supernova is still fading, we would prefer a later execution date so that it is as faint as possible in the proposed imaging. Taking into account the visibility window per orbit and the time needed for guide star acquisition, dithering, and exposure overheads, the total effective exposure time per orbit is 2500 s. We would therefore expect to detect any source at the location of supernova 2017ein with S/N > 20 in F555W and > 10 in F814W. Stellar Physics Stellar Populations 3 false false false false false false false SUPPORTED EXT-STAR SUPERNOVA NO J2000 J2000 WFC3/UVIS Imaging No No F555W WFC3/UVIS Imaging No No F814W POS-TARG DITHER 0.173 LINE 0.112 false false 81.785 4 23.884 WFC3-UVIS-DITHER-BOX 1 false The scheduling data was generated by CASM 27.0. CASM was run in Phase II mode. 1573147103000 318.8371730364061 (Tic-Visit :proposal-id 15691 :visit-id "01" :proposal-version -1 :trans-version "20181130" :date "26-Apr-2019 13:28:52.0" :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 2310000 :tdrss-contact-duration 0 :coron NIL ) (Tic-Obset :proposal-id 15691 :visit-id "01" :obset-id "01" :pcs-mode "FGS" ) (Tic-Orbit :proposal-id 15691 :visit-id "01" :orbit-number 1 :pcs-time 333 :si-vis-utilization 2905 :al-overhead-at-end 116 :internal-dur-at-end 0 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 3238 :pcs-gap 0 ) (Tic-Orbit :proposal-id 15691 :visit-id "01" :orbit-number 2 :pcs-time 302 :si-vis-utilization 2936 :al-overhead-at-end 116 :internal-dur-at-end 668 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 3238 :pcs-gap 0 ) true 2 0 (Tic-Visit :proposal-id 15691 :visit-id "01" :proposal-version -1 :trans-version "20181130" :date "26-Apr-2019 13:28:52.0" :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 2310000 :tdrss-contact-duration 0 :coron NIL ) (Tic-Obset :proposal-id 15691 :visit-id "01" :obset-id "01" :pcs-mode "FGS" ) (Tic-Orbit :proposal-id 15691 :visit-id "01" :orbit-number 1 :pcs-time 333 :si-vis-utilization 2905 :al-overhead-at-end 116 :internal-dur-at-end 0 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 3238 :pcs-gap 0 ) (Tic-Orbit :proposal-id 15691 :visit-id "01" :orbit-number 2 :pcs-time 302 :si-vis-utilization 2936 :al-overhead-at-end 116 :internal-dur-at-end 668 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 3238 :pcs-gap 0 ) false 2 0