Supernovae (SNe) have a profound effect on galaxies, and have been used recently as precise cosmological probes, resulting in the discovery of the accelerating Universe. They are clearly very important events deserving of intense study. Yet, even with nearly 4000 known SNe, we know relatively little about the stars which give rise to these powerful explosions. The main limitation has been the lack of spatial resolution in pre-SN imaging data. However, since 1999 our team has been at the vanguard of directly identifying SN progenitor stars in HST images. From this exciting new line of study, the emerging trend from 5 detections for Type II-Plateau SNe is that their progenitors appear to be relatively low mass (8 to 20 Msun) red supergiants, although more cases are needed. Nonetheless, the nature of the progenitors of Type Ib/c SNe, a subset of which are associated with the amazing gamma-ray bursts, remains ambiguous. Furthermore, we remain in the continually embarrassing situation that we still do not yet know which progenitor systems explode as Type Ia SNe, which are currently being used for precision cosmology. We propose to confirm the identities of the progenitors of 4 SNe within 17 Mpc, which we expect to occur during Cycle 16, through ToO observations using WFPC2/PC.

We plan for four ToO triggers during Cycle 16. Generally, if we detect one or more candidate stellar objects within a 1-sigma positional uncertainty in ACS or WFPC2 pre-supernova archival image(s), we will request a trigger to confirm the progenitor candidate. We request imaging with WFPC2/PC, to provide the highest possible spatial resolution. Imaging will be in two bands, generally V (F555W) and I (F814W). We will likely request triggers when the SN is still fairly bright, depending on its age at discovery, but limit this to m>~13 mag. The imaging will be done in pairs of short and long exposures per band. If we are very fortunate to have a nearby (<~ 6 Mpc) SN Ia occur, we will image in pairs of U (F336W) and B (F439W) exposures, since these SNe will likely be too bright in the redder bands, but fade more rapidly in the blue. The ToOs are not at all urgent, and the SNe can be imaged many months after explosion, so there should be no disruption of normal scheduling. We will not place constraints on the observations, given the two-gyro operational mode. We request triggers with exposures of 40s/800s in F555W and 20s/700s in F814W, with possibly one trigger with exposures of 80s/1000s in F336W and 40s/500s in F439W, in CR splits with WFPC2/PC. HOT STARS 0 false 0.0 0.0 false false false false false SUPPORTED STAR SUPERNOVA SUPERNOVA TYPE IB J2000 00 00 0.0000 +00 00 0.00 J2000 STAR SUPERNOVA J2000 00 00 0.0000 +00 00 0.00 J2000 STAR SUPERNOVA SUPERNOVA TYPE II J2000 00 00 0.0000 +00 00 0.00 J2000 STAR SUPERNOVA J2000 00 00 0.0000 +00 00 0.00 J2000 WFPC2 Imaging No F555W WFPC2 Imaging No F814W WFPC2 Imaging No F555W WFPC2 Imaging No F814W WFPC2 Imaging No F555W WFPC2 Imaging No F814W WFPC2 Imaging No F336W WFPC2 Imaging No F439W The scheduling data was generated by CASM 17.0. CASM was run in Phase II mode. 1193682442000 197.23930941039453 (Tic-Visit :proposal-id 11119 :visit-id "01" :proposal-version -1 :trans-version "20071214" :date "21-Apr-2008 07:30:08.0" :trans-errors '(:WARNINGS 0 :ERRORS 0 :HEALTH-AND-SAFETY 0 :FATAL-ERRORS 0 :CONTINUABLE-FATALS 0) :number-of-orbits 1 :saa-model "26" :si-bright-earth-limb-angle 20.0 :data-volume 672240 :tdrss-contact-duration 0 :coron NIL ) (Tic-Obset :proposal-id 11119 :visit-id "01" :obset-id "01" :pcs-mode "FGS" ) (Tic-Orbit :proposal-id 11119 :visit-id "01" :orbit-number 1 :pcs-time 355 :si-vis-utilization 2700 :al-overhead-at-end 120 :internal-dur-at-end 0 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 3159 :pcs-gap 0 ) false 1 0 The scheduling data was generated by CASM 17.0. CASM was run in Phase II mode. 1210919223000 132.312285441134 (Tic-Visit :proposal-id 11119 :visit-id "02" :proposal-version -1 :trans-version "20071214" :date "21-Apr-2008 07:30:11.0" :trans-errors '(:WARNINGS 0 :ERRORS 0 :HEALTH-AND-SAFETY 0 :FATAL-ERRORS 0 :CONTINUABLE-FATALS 0) :number-of-orbits 1 :saa-model "26" :si-bright-earth-limb-angle 20.0 :data-volume 672240 :tdrss-contact-duration 0 :coron NIL ) (Tic-Obset :proposal-id 11119 :visit-id "02" :obset-id "02" :pcs-mode "FGS" ) (Tic-Orbit :proposal-id 11119 :visit-id "02" :orbit-number 1 :pcs-time 355 :si-vis-utilization 2700 :al-overhead-at-end 120 :internal-dur-at-end 0 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 3169 :pcs-gap 0 ) false 1 0 ToO The scheduling data was generated by CASM 17.2. CASM was run in Phase II mode. (Tic-Visit :proposal-id 11119 :visit-id "03" :proposal-version -1 :trans-version "20080624" :date "02-Jul-2008 17:36:44.0" :trans-errors '(:WARNINGS 0 :ERRORS 0 :HEALTH-AND-SAFETY 0 :FATAL-ERRORS 0 :CONTINUABLE-FATALS 0) :number-of-orbits 1 :saa-model "26" :si-bright-earth-limb-angle 20.0 :data-volume 672240 :tdrss-contact-duration 0 :coron NIL ) (Tic-Obset :proposal-id 11119 :visit-id "03" :obset-id "03" :pcs-mode "FGS" ) (Tic-Orbit :proposal-id 11119 :visit-id "03" :orbit-number 1 :pcs-time 355 :si-vis-utilization 2700 :al-overhead-at-end 120 :internal-dur-at-end 0 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 3169 :pcs-gap 0 ) false 1 0 The scheduling data was generated by CASM 17.0. CASM was run in Phase II mode. (Tic-Visit :proposal-id 11119 :visit-id "04" :proposal-version -1 :trans-version "20071214" :date "21-Apr-2008 07:30:13.0" :trans-errors '(:WARNINGS 0 :ERRORS 0 :HEALTH-AND-SAFETY 0 :FATAL-ERRORS 0 :CONTINUABLE-FATALS 0) :number-of-orbits 1 :saa-model "26" :si-bright-earth-limb-angle 20.0 :data-volume 358528 :tdrss-contact-duration 0 :coron NIL ) (Tic-Obset :proposal-id 11119 :visit-id "04" :obset-id "04" :pcs-mode "FGS" ) (Tic-Orbit :proposal-id 11119 :visit-id "04" :orbit-number 1 :pcs-time 355 :si-vis-utilization 2700 :al-overhead-at-end 180 :internal-dur-at-end 0 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 3132 :pcs-gap 0 ) false 1 0 ToO