Assigned ID: 603 ----- Attempting Submission 1 (Fri Feb 24 19:19:36 GMT 2012) ----- ----- Attempting Submission 1 (Mon Jul 02 11:36:20 GMT 2012) ----- Despite the tremendous importance of type Ia supernovae (SNe Ia), from their use as cosmological distance indicators to their contribution to the chemical enrichment of the Universe, we are still puzzled by the basic questions: what are their progenitor systems and how do they explode? Peculiar SNe Ia, objects that resemble normal SNe Ia spectroscopically, but lie off the one-parameter Phillips relationship the vast majority of SN Ia follow, play a useful role in answering these questions. By understanding what makes a small, but significant, fraction of SNe Ia different than their normal cousins, we may identify the key initial conditions and physical processes at work. Here we propose late-time HST WFC3/UVIS optical photometry of SN 2012Z, the most recent member of the peculiar SN 2002cx-like subclass of SNe Ia. We will compare our observations with extremely deep pre-explosion HST ACS images of the host galaxy NGC 1309, to test whether bright (M_I = -6) stars near the position of the SN are in fact coincident with it, testing a massive star progenitor hypothesis for this subclass of explosions, contrary to the most likely progenitor models for normal SNe Ia. We will also continue to follow the optical light curve of SN 2012Z to epochs later than any peculiar SNe Ia has been observed, in order to test signatures of explosion models for these objects. We propose to obtain late-time optical WFC3/UVIS VrI photometry of SN 2012Z in NGC 1309 in two epochs, once during Cycle 20 (sometime approximately 400 to 600 days after SN maximum light), and again during Cycle 21 (sometime approximately 750 to 950 days past maximum). In the first epoch observations (between March and September 2013) we anticipate SN 2012Z will have V~22.3, r~22.5, and I~22.5, with an uncertainty of about 1 mag. To accurately measure the position of the SN, we require S/N >~ 20 in F555W, even in a pessimistic case (with the SN 1 mag below the prediction and near the end of the observing window). Based on the WFC3/UVIS exposure time calculator, and including overheads and two dithered exposures in each filter, our first epoch observations will fit comfortably within one orbit. The second epoch (Cycle 21) observations in 3 orbits will be submitted separately. HOT STARS 12 false 0.0 0.0 false false false false SUPPORTED EXT-STAR SUPERNOVA TYPE IA J2000 J2000 fading WFC3/UVIS Imaging No No F555W WFC3/UVIS Imaging No No F625W WFC3/UVIS Imaging No No F814W WFC3/UVIS Imaging No No F555W WFC3/UVIS Imaging No No F625W WFC3/UVIS Imaging No No F814W 1340995787962 /Users/saurabh/proposals/hst.cycle20.sn12Z/phase2/OP-cache/sn2012z-phase2-v01.xml The scheduling data was generated by CASM 20.2. CASM was run in Phase II mode. (Tic-Visit :proposal-id 12913 :visit-id "01" :proposal-version -1 :trans-version "20120604" :date "29-Jun-2012 14:49:47.0" :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 1732496 :tdrss-contact-duration 0 :coron NIL ) (Tic-Obset :proposal-id 12913 :visit-id "01" :obset-id "01" :pcs-mode "FGS" ) (Tic-Orbit :proposal-id 12913 :visit-id "01" :orbit-number 1 :pcs-time 333 :si-vis-utilization 2681 :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 3015 :pcs-gap 0 ) true 1 0