12170( 2) - 06-Jul-2010 19:03:57 - [ 1] HUBBLE SPACE TELESCOPE OBSERVING PROGRAM 12170 Version: 2 Check-in Time: 06-Jul-2010 19:03:57 STScI Edit Number: 0 Title A direct UV search for the progenitor of the nearby type Ib SN 2007fo ------------------------------------------------------------------------------------ Type Cycle GO 18 ------------------------------------------------------------------------------------ Investigators Contact? PI: Dr. Avishay Gal-Yam Weizmann Institute of Science CoI: Mr. Yoav Green Weizmann Institute of Science N CoI: Dr. Douglas C. Leonard San Diego State University N CoI: Dr. Derek B. Fox The Pennsylvania State University N ------------------------------------------------------------------------------------ Abstract Understanding the explosive death of massive stars is a key open question in astrophysics. Direct observational information about the pre-explosion properties of supernova progenitors would provide explosion models with a set of initial conditions, and a crucial complement to supernova observations that constrain the explosive outcome. In recent years, identifying the progenitors of the most nearby supernovae in pre-explosion HST images has allowed significant progress in this field. However, this is limited mostly to H-rich type II supernova explosions of red supergiants. The improtant class of stripped (H-poor) type Ib and Ic supernovae, which are especially interesting due to their possible relation to long Gamma-Ray Bursts, remain obscure, with many attempts to discover progenitors yielding only upper limits. The hunt for these elusive progenitors is difficult probably due to a combination of factors: SN Ib/c are intrinsically rare, and their stripped progenitors (probably blue Wolf-Rayet stars) are difficult to detect in archival pre-explosion HST images, mostly obtained in red bands. The nearby type Ib SN 2007fo exploded in NGC 7714, a galaxy with archival imaging uniquely extending to the UV. We have used ground-based Gemini AO imaging of the supernova to localize it on the pre-explosion HST grid, and found that it resides in a complicated area where a single progenitor cannot be pinpointed (though candidates exist). Next, we propose to reimage this location and compare the post-explosion images to archival templates in order to robustly identify the progenitor. Using image-subtraction we will compare the two HST epochs, identify objects that decay or disappear, and thus locate the progenitor of this SN, a very exciting prospect. Failing to detect the progenitor would place strong limits on its luminosity, adding to the growing body of information on SN progenitors. A modest investment of 2 HST orbits has the potential to reveal the first W-R progenitor of a type Ib supernova. ------------------------------------------------------------------------------------ Observations Description ------------------------ We will observe the location of SN 2007fo in the optical with ACS (1 orbit, split between F814W and F606W) and the UV with WFC3/UVIS (1 orbit split between F390W and F300X). Filters were selected to match available pre-explosion data, and durations were tuned to exceed the sensitivity of the reference data set in all bands, while maximizing orbit use efficiency. 12170( 2) - 06-Jul-2010 19:03:57 - [ 2] Real Time Justification ----------------------- Calibration Justification ------------------------- Additional Comments ------------------- ------------------------------------------------------------------------------------ 12170( 2) - 06-Jul-2010 19:03:57 - [ 3] TARGET LIST Fixed Targets ------------------------------------------------------------------------------------------------------------------------------------ Tar| Target | Target | Target |Coord | Radial | Flux data No | Name | Description | Position |Eqnx | Vel. | ------------------------------------------------------------------------------------------------------------------------------------ 1 SN2007FO EXT-STAR, SUPERNOVA, RA=23H36M14.0000S +/- 0.1", J2000 V = 25 SUPERNOVA TYPE IB DEC=+02D09'30.00" +/- 0.1" Reference Frame: ICRS Comments: ------------------------------------------------------------------------------------------------------------------------------------ 12170( 2) - 06-Jul-2010 19:03:57 - [ 4] Patterns ------------------------------------------------------------------------------------------------------------------------------------ Pattern_Number: 1 Primary_Pattern Secondary_Pattern Pattern_Type ACS-WFC-DITHER-BOX Pattern_Purpose DITHER Number_Of_Points 4 Point_Spacing 0.265 Line_Spacing 0.187 Coordinate_Frame POS-TARG Pattern_Orient 20.67 Angle_Between_Sides 69.05 Center_Pattern NO ------------------------------------------------------------------------------------------------------------------------------------ Pattern_Number: 2 Primary_Pattern Secondary_Pattern Pattern_Type WFC3-UVIS-DITHER-BOX Pattern_Purpose DITHER Number_Of_Points 4 Point_Spacing 0.173 Line_Spacing 0.112 Coordinate_Frame POS-TARG Pattern_Orient 23.884 Angle_Between_Sides 81.785 Center_Pattern NO ------------------------------------------------------------------------------------------------------------------------------------ 12170( 2) - 06-Jul-2010 19:03:57 - [ 5] Visit: 01 Visit Requirements: On Hold Comments: Additional Comments: Exposures ------------------------------------------------------------------------------------------------------------------------------------ Exp | Target | Instr | Oper. | Aper |Spectral|Central| Optional |Num| Time | Special Num | Name | Config | Mode | or FOV |Element |Waveln.| Parameters |Exp| | Requirements ------------------------------------------------------------------------------------------------------------------------------------ 1 SN2007FO ACS/WFC ACCUM WFC1 F814W 1 97 S ------------------------------------------------------------------------------------------------------------------------------------ 2 SN2007FO ACS/WFC ACCUM WFC1 F606W 1 340 S PATTERN 1 2 ------------------------------------------------------------------------------------------------------------------------------------ 3 SN2007FO ACS/WFC ACCUM WFC1 F814W 1 340 S ------------------------------------------------------------------------------------------------------------------------------------ Sub Exposures ------------------------------------------------------------------------------------------------------------------------------------ Target | Exp |Instr | Oper. | Aper |Spectral|Cent.|Primary |Secondary |Iteration |CR-SPLIT |Orbit |Duration Name | Num |Config | Mode | or FOV |Element |Wave.|Pattern Pos |Pattern Pos |Num |Num |Number | ------------------------------------------------------------------------------------------------------------------------------------ SN2007FO 1 ACS/WFC ACCUM WFC1 F814W none none none none 1 N/A SN2007FO 2 ACS/WFC ACCUM WFC1 F606W 1 none none none 1 N/A SN2007FO 2 ACS/WFC ACCUM WFC1 F606W 2 none none none 1 N/A SN2007FO 2 ACS/WFC ACCUM WFC1 F606W 3 none none none 1 N/A SN2007FO 2 ACS/WFC ACCUM WFC1 F606W 4 none none none 1 N/A SN2007FO 3 ACS/WFC ACCUM WFC1 F814W none none none none 1 N/A 12170( 2) - 06-Jul-2010 19:03:57 - [ 6] Visit: 02 Visit Requirements: On Hold Comments: Additional Comments: Exposures ------------------------------------------------------------------------------------------------------------------------------------ Exp | Target | Instr | Oper. | Aper |Spectral|Central| Optional |Num| Time | Special Num | Name | Config | Mode | or FOV |Element |Waveln.| Parameters |Exp| | Requirements ------------------------------------------------------------------------------------------------------------------------------------ 1 SN2007FO WFC3/UVI ACCUM UVIS1 F390W 1 370 S PATTERN 2 1 S see below ------------------------------------------------------------------------------------------------------------------------------------ 2 SN2007FO WFC3/UVI ACCUM UVIS1 F300X CR-SPLIT=2 1 399 S S see below ------------------------------------------------------------------------------------------------------------------------------------ Sub Exposures ------------------------------------------------------------------------------------------------------------------------------------ Target | Exp |Instr | Oper. | Aper |Spectral|Cent.|Primary |Secondary |Iteration |CR-SPLIT |Orbit |Duration Name | Num |Config | Mode | or FOV |Element |Wave.|Pattern Pos |Pattern Pos |Num |Num |Number | ------------------------------------------------------------------------------------------------------------------------------------ SN2007FO 1 WFC3/UVI ACCUM UVIS1 F390W 1 none none none 1 368.0 S S SN2007FO 1 WFC3/UVI ACCUM UVIS1 F390W 2 none none none 1 368.0 S S SN2007FO 1 WFC3/UVI ACCUM UVIS1 F390W 3 none none none 1 368.0 S S SN2007FO 1 WFC3/UVI ACCUM UVIS1 F390W 4 none none none 1 368.0 S S SN2007FO 2 WFC3/UVI ACCUM UVIS1 F300X none none none 1 1 400.0 S S SN2007FO 2 WFC3/UVI ACCUM UVIS1 F300X none none none 2 1 360.0 S S 12170( 2) - 06-Jul-2010 19:03:57 - [ 7] Summary Form for Proposal 12170 Item Used in this proposal ------------------------------------------------------------------------------------------------------------------------------------ Apertures UVIS1, WFC1 ------------------------------------------------------------------------------------------------------------------------------------ Configurations ACS/WFC, WFC3/UVIS ------------------------------------------------------------------------------------------------------------------------------------ Opmodes ACCUM ------------------------------------------------------------------------------------------------------------------------------------ Optional Parameters CR-SPLIT=2 ------------------------------------------------------------------------------------------------------------------------------------ Special Requirements PATTERN 1 2, PATTERN 2 1 ------------------------------------------------------------------------------------------------------------------------------------ Spectral Elements F300X, F390W, F606W, F814W ------------------------------------------------------------------------------------------------------------------------------------ Target Names SN2007FO ------------------------------------------------------------------------------------------------------------------------------------