Update to Visit 2. NSAMPS adjusted for better CR rejection - WFC3/IR observations use 512x512 subarray, 1 iteration each for F125W and F160W imaging (with 4 point dither pattern). ----- Attempting Submission 3 (Fri Dec 03 14:59:55 GMT 2010) ----- ----- Attempting Submission 4 (Sun Mar 27 12:24:23 GMT 2011) ----- Recent studies have used high spatial resolution HST observations of supernova (SN) sites to directly identify the progenitors of core-collapse SNe on pre-explosion images. These studies have set constraints about the nature of massive stars and their evolution just prior to their explosion as SNe. Now, at late-times when the SNe have faded sufficiently, it is possible to return to the sites of these core-collapse SNe to search for clues about the nature of their progenitors. We request time to conduct deep, late-time, high-resolution imaging with WFC3/UVIS+IR and ACS/WFC of the sites of three core-collapse SNe 2008ax, 2008bk and 2008cn. We aim to: 1) Confirm our original identifications, made in pre-explosion images, by confirming that the progenitors are now missing; 2) Apply image subtraction techniques for this late-time imaging with our pre-explosion images to determine accurate photometry of the progenitors to constrain their temperatures and luminosities; and 3) study the stellar populations in the immediate vicinities of these SNe, previously obscured by the progenitor and the SN, to provide a measure of the progenitor's age, as well. For SN 2008ax we aim to determine the possible presence of a binary companion, as a persistent source at the SN location once the SN has faded and the progenitor has disappeared. HST provides the unique combination of high-resolution optical/IR imaging at very faint magnitudes that will facilitate this study.

We require imaging of three SN sites with pre-explosion observations in which the progenitors were detected. We aim to confirm the progenitor identification, through the stars' disappearance - and accurately measure the progenitors' photometric properties using image subtraction techniques. Multi-colour imaging will be used to probe the nature of the surrounding stellar population. The bands in which the SN sites will be observed are dictated by the nature of the available pre-explosion imaging. The three SN sites to be observed are those of SN 2008ax (3 orbits), 2008bk (1 orbit), 2008cn (2 orbits). Each SN site is to be visited once. In order to improve the spatial sampling, and improve the resolution, all observations are grouped into box dither patterns. To minimize the amount of time lost to reading out the detectors, subarrays will be adopted SN2008ax - WFC3 UVIS 1kx1k - Visit 1 - 3 orbits U F336W to reach down to 26 @ 3sigma B F438W to reach down to 27 @ 3 sigma V F606W to reach down to 27@ 5 sigma R F625W to reach down to 26.5 @ 3 sigma I F814W to reach down to 26.5 @ 3sigma all exposures times have been selected to only saturate stars above the limit of X ~ 20 (in Vega mags) in all bands SN2008bk - WFC3 UVIS 1kx1k & IR 512x512 - Visit 2 - 1 orbit I F814W UVIS to reach down to I=26 at 3 sigma J F125W IR to reach down to J=24 at 5 sigma (3 iterations of 4x2xSPAR25 - i.e. 4x50s exposures) - with this observation we are balancing the need for depth, against the possibility of saturating on surrounding stars (which we would also like to observe, as well as to avoid persistance issues with the detector) - estimate that the saturation limit J=17 should be brighter than surrounding stars H 160W IR to reach down to H = 24 at 3 sigma - similar ot the J band obs, use 2 iterations of 4x4xSPAR25 to avoid saturating stars up to limit of H=16.5 512x512 subarray is required to avoid being penalised by readout time SN2008cn - ACS/WFC 1kx1k - Visit 3 - 2 orbits B F435W to reach down to 27.5 at 3sigma V F555W to reach down to 27.5 at 3sigma I F814W to reach down to 27 at 3sigma Again saturation limit is set for stars brighter than X ~ 20 (vega mags) Further to our request in the Phase I proposal, we have requested that the SN2008cn observation (visit 3) be scheduled in the second half of Cycle 18 - i.e. after Feb 1st 2011 No special calibrations are required HOT STARS 12 false 0.0 0.0 false false false false SUPPORTED EXT-STAR SUPERNOVA This object was generated by the targetselector and retrieved from the NED database. J2000 00 00 0.0000 +00 00 0.00 J2000 EXT-STAR SUPERNOVA This object was generated by the targetselector and retrieved from the SIMBAD database. J2000 00 00 0.0000 +00 00 0.00 J2000 EXT-STAR SUPERNOVA This object was generated by the targetselector and retrieved from the SIMBAD database. J2000 00 00 0.0000 +00 00 0.00 J2000 WFC3/UVIS Imaging No No F438W WFC3/UVIS Imaging No No F606W WFC3/UVIS Imaging No No F814W WFC3/UVIS Imaging No No F336W WFC3/UVIS Imaging No No F625W WFC3/IR Imaging No No F125W WFC3/IR Imaging No No F160W WFC3/UVIS Imaging No No F814W ACS/WFC Imaging No No F435W ACS/WFC Imaging No No F555W ACS/WFC 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 POS-TARG DITHER 0.572 LINE 0.365 false false 74.653 4 18.528 WFC3-IR-DITHER-BOX-MIN 2 false POS-TARG DITHER 0.265 LINE 0.187 false false 69.05 4 20.67 ACS-WFC-DITHER-BOX 3 false The scheduling data was generated by CASM 18.3.1. CASM was run in Phase II mode. Visit for SN2008AX (Tic-Visit :proposal-id 12262 :visit-id "01" :proposal-version -1 :trans-version "20100505" :date "30-Jul-2010 13:27:41.0" :trans-errors '(:WARNINGS 0 :ERRORS 0 :HEALTH-AND-SAFETY 0 :FATAL-ERRORS 0 :CONTINUABLE-FATALS 0) :number-of-orbits 3 :saa-model "29" :si-bright-earth-limb-angle 20.0 :data-volume 356496 :tdrss-contact-duration 0 :coron NIL ) (Tic-Obset :proposal-id 12262 :visit-id "01" :obset-id "01" :pcs-mode "FGS" ) (Tic-Orbit :proposal-id 12262 :visit-id "01" :orbit-number 1 :pcs-time 333 :si-vis-utilization 3007 :al-overhead-at-end 74 :internal-dur-at-end 0 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 3341 :pcs-gap 0 ) (Tic-Orbit :proposal-id 12262 :visit-id "01" :orbit-number 2 :pcs-time 222 :si-vis-utilization 3116 :al-overhead-at-end 74 :internal-dur-at-end 0 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 3341 :pcs-gap 0 ) (Tic-Orbit :proposal-id 12262 :visit-id "01" :orbit-number 3 :pcs-time 222 :si-vis-utilization 3115 :al-overhead-at-end 74 :internal-dur-at-end 428 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 3341 :pcs-gap 0 ) true 3 0 The scheduling data was generated by CASM 19.0. CASM was run in Phase II mode. /private/var/folders/OD/OD2CkRasEAS7tTpuc9uy6E++CfQ/-Tmp-/OPVisit8239369040872327122.xml 1301228144677 Visit for SN2008BK (Tic-Visit :proposal-id 12262 :visit-id "02" :proposal-version -1 :trans-version "20100902" :date "27-Mar-2011 14:15:44.0" :trans-errors '(:WARNINGS 0 :ERRORS 0 :HEALTH-AND-SAFETY 0 :FATAL-ERRORS 0 :CONTINUABLE-FATALS 0) :number-of-orbits 1 :saa-model "29" :si-bright-earth-limb-angle 20.0 :data-volume 398480 :tdrss-contact-duration 0 :coron NIL ) (Tic-Obset :proposal-id 12262 :visit-id "02" :obset-id "02" :pcs-mode "FGS" ) (Tic-Orbit :proposal-id 12262 :visit-id "02" :orbit-number 1 :pcs-time 241 :si-vis-utilization 3034 :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 3275 :pcs-gap 0 ) true 1 0 The scheduling data was generated by CASM 18.3.1. CASM was run in Phase II mode. Visit for SN2008CN (Tic-Visit :proposal-id 12262 :visit-id "03" :proposal-version -1 :trans-version "20100505" :date "30-Jul-2010 13:27:46.0" :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 213328 :tdrss-contact-duration 0 :coron NIL ) (Tic-Obset :proposal-id 12262 :visit-id "03" :obset-id "03" :pcs-mode "FGS" ) (Tic-Orbit :proposal-id 12262 :visit-id "03" :orbit-number 1 :pcs-time 333 :si-vis-utilization 3006 :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 3341 :pcs-gap 0 ) (Tic-Orbit :proposal-id 12262 :visit-id "03" :orbit-number 2 :pcs-time 222 :si-vis-utilization 3113 :al-overhead-at-end 0 :internal-dur-at-end 272 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 3341 :pcs-gap 0 ) true 2 0