12331( 3) - 22-Jul-2010 13:03:14 - [ 1] HUBBLE SPACE TELESCOPE OBSERVING PROGRAM 12331 Version: 3 Check-in Time: 22-Jul-2010 13:03:14 STScI Edit Number: 0 Title Massive Star CSI: Has The Progenitor of SN2008S Vanished? ------------------------------------------------------------------------------------ Type Cycle GO 18 ------------------------------------------------------------------------------------ Investigators Contact? PI: Dr. C. S. Kochanek The Ohio State University Research Foundation CoI: Dr. Krzysztof Z. Stanek The Ohio State University Research N Foundation CoI: Dr. Jose Luis Prieto Carnegie Institution of Washington N CoI: Dr. Todd A. Thompson The Ohio State University Research N Foundation ------------------------------------------------------------------------------------ Abstract SN2008S in NGC6946 is the prototype of a new class of optical transients. Its luminosity was low for a Type II supernova, and the progenitor star was identified as a completely dust obscured log (L/Lsun)=4.5, T=440K massive star (~10 Msun) in archival Spitzer data. It is uncertain whether this is a new class of low?luminosity supernova (e.g. an electron capture supernova) or a new class of massive star outburst. The transient has now faded to the point where the source is again invisible in the optical. Near?IR detections are consistent with a somewhat hotter source, T~1200K, somewhat brighter than the progenitor and still fading at ~3 mag/year. Using two epochs of IRAC observations to constrain the mid?IR emission, and two epochs of HST H?band/J-band observations to constrain emission from cool stars, we will solve this mystery by either identifying and characterizing the surviving progenitor or ruling out its survival. ------------------------------------------------------------------------------------ Observations Description ------------------------ We will obtain two epochs of WFC3/IR images of the transient SN2008S in NGC6946 separated by at least 6 months. The goal is to identify the transient in the near-IR relative to our ground based images, determine it's magnitude and rate of fading compared to the estimated luminosity of massive stars, and characterize its environment (crowding). This will be matched to a set of Warm Spitzer observations at 3.6 and 4.5 to constrain the luminosity in emission by warm dust. The primary observations are the WFC3/IR H-band (F160W) observations. We will obtain 3 dithered MULTIACCUM H-band observations in each epoch. We also obtain a single J-band image. Given the overheads created by buffer dumps it was not possible to obtain multiple dithers in the second filter. However, by combining 12331( 3) - 22-Jul-2010 13:03:14 - [ 2] the J-band images from the two epochs we will obtain a high quality image. This J band data will be used to characterize the region around SN2008S and the other 3 SN in the WFC3/IR field of view. We also include ACS/WFC I (F184W) and V (F555W) parallels. The goal here is simply to build the archival data base for NGC6946 with deep, high quaility data. A loose orient restriction will keep the WFC on some part of the galaxy, and the epoch 1/2 orients are required to be the same. This seems to cause no scheduling difficulties given the timing requirement of the primary observations. For most possible orientations 1 or 2 of the addition SN in N6946 will lie in the ACS field of view. This revised version uses a 3pt line dither for F160W followed by a F110W exposure. A pos targ from the last H band observation is used in epoch 1 but not in epoch 2 to produce an effective dithering of the two J band observations. Real Time Justification ----------------------- Calibration Justification ------------------------- Additional Comments ------------------- ------------------------------------------------------------------------------------ 12331( 3) - 22-Jul-2010 13:03:14 - [ 3] TARGET LIST Fixed Targets ------------------------------------------------------------------------------------------------------------------------------------ Tar| Target | Target | Target |Coord | Radial | Flux data No | Name | Description | Position |Eqnx | Vel. | ------------------------------------------------------------------------------------------------------------------------------------ 2 SN2008S EXT-STAR, SUPERNOVA RA=20H34M46.5000S +/- 0.1", J2000 V = 25 DEC=+60D06'41.00" +/- 0.1" Reference Frame: ICRS Comments: ------------------------------------------------------------------------------------------------------------------------------------ 12331( 3) - 22-Jul-2010 13:03:14 - [ 4] Patterns ------------------------------------------------------------------------------------------------------------------------------------ Pattern_Number: 1 Primary_Pattern Secondary_Pattern Pattern_Type WFC3-IR-DITHER-LINE-3PT Pattern_Purpose DITHER Number_Of_Points 3 Point_Spacing 0.605 Line_Spacing Coordinate_Frame POS-TARG Pattern_Orient 41.788 Angle_Between_Sides Center_Pattern NO ------------------------------------------------------------------------------------------------------------------------------------ 12331( 3) - 22-Jul-2010 13:03:14 - [ 5] Visit: 01 Visit Requirements: ORIENT 80D TO 220 D 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 SN2008S WFC3/IR MULTIAC IR-FIX F160W NSAMP=13, SAMP-SEQ=STEP100 1 DEF POS TARG 0.52, 0.195; CUM PATTERN 1 1-2; PAR 2 WITH 1 ------------------------------------------------------------------------------------------------------------------------------------ 2 ANY ACS/WFC ACCUM WFC F814W 1 550 S see below ------------------------------------------------------------------------------------------------------------------------------------ 3 SN2008S WFC3/IR MULTIAC IR-FIX F110W NSAMP=14, SAMP-SEQ=STEP100 1 DEF POS TARG 0.325, 0.52; CUM PAR 4 WITH 3 ------------------------------------------------------------------------------------------------------------------------------------ 4 ANY ACS/WFC ACCUM WFC F814W 1 550 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 | ------------------------------------------------------------------------------------------------------------------------------------ SN2008S 1 WFC3/IR MULTIAC IR-FIX F160W 1 none none none 1 N/A CUM SN2008S 1 WFC3/IR MULTIAC IR-FIX F160W 2 none none none 1 N/A CUM SN2008S 1 WFC3/IR MULTIAC IR-FIX F160W 3 none none none 1 N/A CUM ANY 2 ACS/WFC ACCUM WFC F814W 1 none none none 1 521.0 S ANY 2 ACS/WFC ACCUM WFC F814W 2 none none none 1 603.0 S ANY 2 ACS/WFC ACCUM WFC F814W 3 none none none 1 603.0 S SN2008S 3 WFC3/IR MULTIAC IR-FIX F110W none none none none 1 N/A CUM ANY 4 ACS/WFC ACCUM WFC F814W none none none none 1 703.0 S 12331( 3) - 22-Jul-2010 13:03:14 - [ 6] Visit: 02 Visit Requirements: SAME ORIENT AS 01; AFTER 01 BY 180 D TO 365 D 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 SN2008S WFC3/IR MULTIAC IR-FIX F160W NSAMP=13, SAMP-SEQ=STEP100 1 DEF POS TARG 0.52, 0.195; CUM PATTERN 1 1-2; PAR 2 WITH 1 ------------------------------------------------------------------------------------------------------------------------------------ 2 ANY ACS/WFC ACCUM WFC F555W 1 550 S see below ------------------------------------------------------------------------------------------------------------------------------------ 3 SN2008S WFC3/IR MULTIAC IR-FIX F110W NSAMP=14, SAMP-SEQ=STEP100 1 DEF PAR 4 WITH 3 CUM ------------------------------------------------------------------------------------------------------------------------------------ 4 ANY ACS/WFC ACCUM WFC F555W 1 550 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 | ------------------------------------------------------------------------------------------------------------------------------------ SN2008S 1 WFC3/IR MULTIAC IR-FIX F160W 1 none none none 1 N/A CUM SN2008S 1 WFC3/IR MULTIAC IR-FIX F160W 2 none none none 1 N/A CUM SN2008S 1 WFC3/IR MULTIAC IR-FIX F160W 3 none none none 1 N/A CUM ANY 2 ACS/WFC ACCUM WFC F555W 1 none none none 1 521.0 S ANY 2 ACS/WFC ACCUM WFC F555W 2 none none none 1 603.0 S ANY 2 ACS/WFC ACCUM WFC F555W 3 none none none 1 603.0 S SN2008S 3 WFC3/IR MULTIAC IR-FIX F110W none none none none 1 N/A CUM ANY 4 ACS/WFC ACCUM WFC F555W none none none none 1 703.0 S 12331( 3) - 22-Jul-2010 13:03:14 - [ 7] Summary Form for Proposal 12331 Item Used in this proposal ------------------------------------------------------------------------------------------------------------------------------------ Apertures IR-FIX, WFC ------------------------------------------------------------------------------------------------------------------------------------ Configurations ACS/WFC, WFC3/IR ------------------------------------------------------------------------------------------------------------------------------------ Opmodes ACCUM, MULTIACCUM ------------------------------------------------------------------------------------------------------------------------------------ Optional Parameters NSAMP=13, NSAMP=14, SAMP-SEQ=STEP100 ------------------------------------------------------------------------------------------------------------------------------------ Special Requirements AFTER 01 BY 180 D TO 365 D, ORIENT 80D TO 220 D, PAR 2 WITH 1, PAR 4 WITH 3, PATTERN 1 1-2, POS TARG 0.325, 0.52, POS TARG 0.52, 0.195, SAME ORIENT AS 01 ------------------------------------------------------------------------------------------------------------------------------------ Spectral Elements F110W, F160W, F555W, F814W ------------------------------------------------------------------------------------------------------------------------------------ Target Names ANY, SN2008S ------------------------------------------------------------------------------------------------------------------------------------