11590( 7) - 23-Jun-2009 17:33:49 - [ 1] HUBBLE SPACE TELESCOPE OBSERVING PROGRAM 11590 Version: 7 Check-in Time: 23-Jun-2009 17:33:49 STScI Edit Number: 2 Title Observing the IR Catastrophe in a Deflagration Type Ia Supernova ------------------------------------------------------------------------------------ Type Cycle GO 17 ------------------------------------------------------------------------------------ Investigators Contact? PI: Dr. Saurabh W. Jha Rutgers the State University of New Jersey CoI: Dr. Alex V. Filippenko University of California - Berkeley N CoI: Dr. Weidong Li University of California - Berkeley N CoI: Mr. Ryan Chornock University of California - Berkeley N CoI: Dr. Ryan Foley University of California - Berkeley N CoI: Mr. Mohan Ganeshalingam University of California - Berkeley N CoI: Dr. Peter Garnavich University of Notre Dame N CoI: Dr. Adam Riess The Johns Hopkins University N ------------------------------------------------------------------------------------ Abstract Our lack of understanding of Type Ia supernova (SN Ia) explosions limits our confidence in their use for cosmology. While there is broad agreement that these objects represent the explosions of white dwarfs, the details of the explosion mechanism are not well-understood. Recently, we have identified an internally homogeneous subclass of SNe Ia whose photometric and spectroscopic peculiarities make them quite distinct from normal SNe Ia. Models suggest we may be seeing the result of an explosion with a subsonic burning front, called a deflagration. We propose to test SN Ia models by obtaining late-time photometry for SN 2008A, a recent, nearby example of this subclass, using ACS and WFC3 on HST. We will accurately measure the late-time photometric decline rate and spectral energy distribution (SED). These observations will allow us to test whether the ejecta contain the large amount of oxygen predicted by certain models. We also aim to detect major evolution of the SED expected due to the "IR catastrophe, " a change in the dominant cooling mechanism in the ejecta, as generically predicted by models but only hinted at by current observations. ------------------------------------------------------------------------------------ Observations Description ------------------------ We aim to constrain the SED of SN 2008A with HST observations at two epochs as the supernova fades: February-March 2009 (400 days after SN maximum light), and June-August 2009 (550 days after maximum). Using optical and near-infrared data, we will measure the SN decline rate and look for color signatures of the "infrared catastrophe" predicted by models. The timing of the two epochs corresponds to the available observability windows for SN 2008A in cycle 17. **REVISED** (current version June 23, 2009) Because of the time-sensitive nature of these observations and the delay in SM4, we have revised the proposal so that our first epoch observations use WFPC2 instead of ACS and WFC3/IR. Thus they can still be scheduled in early 2009; we have opened the observing window from 2009-Jan-15 to 2009-Mar-31 to 11590( 7) - 23-Jun-2009 17:33:49 - [ 2] facilitate two-gryo mode visibility. Because NICMOS will not be available for the first epoch data, we have switched visit03 to WFPC2. Our second-epoch observations (August 2009) have been revised based on the first-epoch data in which we found the SN to be about 1 magnitude fainter than the nominal prediction. We have updated visits 02 and 04 using the new information. We have structured the observations in 4 visits: In the first optical epoch we will observe with WFPC2 in four filters: F555W, F622W, F791W, and F850LP; corresponding to ground-based Vriz. Based on extrapolations of the current data and inferences from other SN 2002cx-like SNe Ia (including our recent cycle 16 experience with SN 2005hk), we anticipate SN 2008A will have V = 23.5, r = 22.5, i = 22.0, and z = 22.0 mag in the first epoch, with an uncertainty of about 1 mag. To meaningfully constrain models, we must achieve S/N >= 10 in all bands, even in the pessimistic case (1 mag below the prediction). The WFPC2 exposure time calculator indicates this can be done comfortably in two orbits, and we can fill the orbits with exposures of 1000, 800, 900, and 1200 seconds in F555W, F622W, F791W, and F850LP, respectively. We will employ the recommended two-point dither to remove cosmic rays and hot pixels; these have been input using POS TARG offsets to minimize telescope motions. We will put the SN on the PC chip, offset towards the readout amplifier to minimize CTE effects. [COMPLETED] In the first epoch (but a separate visit, visit 03 which was formerly NICMOS) we will also add 350 seconds of F850LP exposure to increase the sensitivity, as well as 1500 seconds of dithered F439W exposure to increase the wavelength range of the SED. [COMPLETED] In the second optical epoch (VISIT 02), we will observe with ACS/WFC in three filters: F555W, F625W, and F775W, and we anticipate SN 2008A will have V = 26.5, r = 26.4, and i = 25.3 at that time, with an uncertainty of 0.5 mag. We will fill four orbits, with total exposures of 3750, 3530, and 2484 seconds in F555W, F625W, and F775W, respectively, with box-dithered observations. In this epoch, the ORIENT restrictions (which overlap entirely the available roll ranges) lead us to use the WFC1 aperture to avoid a nearby bright star (HD 9983, V=7.6, about 2 arcmin to the southwest). In the infrared (VISIT 04), we expect J = 25.0 +/- 1 mag for SN 2008A, and require three orbits using WFC3/IR. We use a four-point box dither in each orbit, with the boxes offset slightly from orbit to orbit, near the standard IR aperture. In orbits 2 and 3 we use a standard dither pattern with SPARS50, NSAMP=15 readout. In the first orbit we use specific POS TARG offsets so that we can have two NSAMP=14 and two NSAMP=15 exposures to optimally fill the shorter available exposure time. This yields a total exposure of 8336 seconds. The supernova will be too faint for our originally planned F160W observations. Real Time Justification ----------------------- Calibration Justification ------------------------- 11590( 7) - 23-Jun-2009 17:33:49 - [ 3] Additional Comments ------------------- ------------------------------------------------------------------------------------ 11590( 7) - 23-Jun-2009 17:33:49 - [ 4] TARGET LIST Fixed Targets ------------------------------------------------------------------------------------------------------------------------------------ Tar| Target | Target | Target |Coord | Radial | Flux data No | Name | Description | Position |Eqnx | Vel. | ------------------------------------------------------------------------------------------------------------------------------------ 1 SN-2008A EXT-STAR, SUPERNOVA RA=01H38M17.3800S +/- 0.1", J2000 V = 23.5 +/- 1.0 fading TYPE IA DEC=+35D22'13.70" +/- 0.1" Reference Frame: ICRS Comments: ------------------------------------------------------------------------------------------------------------------------------------ 11590( 7) - 23-Jun-2009 17:33:49 - [ 5] 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-IR-DITHER-BOX-MIN Pattern_Purpose DITHER Number_Of_Points 4 Point_Spacing 0.572 Line_Spacing 0.365 Coordinate_Frame POS-TARG Pattern_Orient 18.528 Angle_Between_Sides 74.653 Center_Pattern NO ------------------------------------------------------------------------------------------------------------------------------------ 11590( 7) - 23-Jun-2009 17:33:49 - [ 6] Visit: 01 Visit Requirements: GYRO MODE 2G; BETWEEN 15-JAN-2009:00:00:01 AND 31-MAR-2009:23:59:59 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 SN-2008A WFPC2 IMAGE PC1 F555W 1 500 S POS TARG -7, -8 ------------------------------------------------------------------------------------------------------------------------------------ 2 SN-2008A WFPC2 IMAGE PC1 F555W 1 500 S POS TARG -6.751, -7.751 ------------------------------------------------------------------------------------------------------------------------------------ 3 SN-2008A WFPC2 IMAGE PC1 F791W 1 500 S POS TARG -6.751, -7.751 ------------------------------------------------------------------------------------------------------------------------------------ 4 SN-2008A WFPC2 IMAGE PC1 F791W 1 400 S POS TARG -7, -8 ------------------------------------------------------------------------------------------------------------------------------------ 5 SN-2008A WFPC2 IMAGE PC1 F622W 1 400 S POS TARG -7, -8 ------------------------------------------------------------------------------------------------------------------------------------ 6 SN-2008A WFPC2 IMAGE PC1 F622W 1 400 S POS TARG -6.751, -7.751 ------------------------------------------------------------------------------------------------------------------------------------ 7 SN-2008A WFPC2 IMAGE PC1 F850LP 1 600 S POS TARG -6.751, -7.751 ------------------------------------------------------------------------------------------------------------------------------------ 8 SN-2008A WFPC2 IMAGE PC1 F850LP 1 500 S POS TARG -7, -8 ------------------------------------------------------------------------------------------------------------------------------------ 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 | ------------------------------------------------------------------------------------------------------------------------------------ SN-2008A 1 WFPC2 IMAGE PC1 F555W none none none none 1 N/A SN-2008A 2 WFPC2 IMAGE PC1 F555W none none none none 1 N/A SN-2008A 3 WFPC2 IMAGE PC1 F791W none none none none 1 N/A SN-2008A 4 WFPC2 IMAGE PC1 F791W none none none none 1 N/A SN-2008A 5 WFPC2 IMAGE PC1 F622W none none none none 2 N/A SN-2008A 6 WFPC2 IMAGE PC1 F622W none none none none 2 N/A SN-2008A 7 WFPC2 IMAGE PC1 F850LP none none none none 2 N/A SN-2008A 8 WFPC2 IMAGE PC1 F850LP none none none none 2 N/A 11590( 7) - 23-Jun-2009 17:33:49 - [ 7] Visit: 02 Visit Requirements: ORIENT 205D TO 295 D; BETWEEN 01-JUN-2009:00:00:01 AND 31-AUG-2009:23:59:59 On Hold Comments: Additional Comments: ORIENT range avoids bright star to the southwest Exposures ------------------------------------------------------------------------------------------------------------------------------------ Exp | Target | Instr | Oper. | Aper |Spectral|Central| Optional |Num| Time | Special Num | Name | Config | Mode | or FOV |Element |Waveln.| Parameters |Exp| | Requirements ------------------------------------------------------------------------------------------------------------------------------------ 1 SN-2008A ACS/WFC ACCUM WFC1 F625W 1 570 S PATTERN 1 1 ------------------------------------------------------------------------------------------------------------------------------------ 2 SN-2008A ACS/WFC ACCUM WFC1 F625W 1 625 S POS TARG 0.198, 0.214 ------------------------------------------------------------------------------------------------------------------------------------ 3 SN-2008A ACS/WFC ACCUM WFC1 F625W 1 625 S POS TARG 0.099, 0.107 ------------------------------------------------------------------------------------------------------------------------------------ 4 SN-2008A ACS/WFC ACCUM WFC1 F555W 1 625 S POS TARG 0.099, 0.107 ------------------------------------------------------------------------------------------------------------------------------------ 5 SN-2008A ACS/WFC ACCUM WFC1 F555W 1 625 S POS TARG 0.198, 0.214 ------------------------------------------------------------------------------------------------------------------------------------ 6 SN-2008A ACS/WFC ACCUM WFC1 F555W 1 625 S PATTERN 1 6 ------------------------------------------------------------------------------------------------------------------------------------ 7 SN-2008A ACS/WFC ACCUM WFC1 F775W 1 621 S PATTERN 1 7 ------------------------------------------------------------------------------------------------------------------------------------ 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 | ------------------------------------------------------------------------------------------------------------------------------------ SN-2008A 1 ACS/WFC ACCUM WFC1 F625W 1 none none none 1 N/A SN-2008A 1 ACS/WFC ACCUM WFC1 F625W 2 none none none 1 N/A SN-2008A 1 ACS/WFC ACCUM WFC1 F625W 3 none none none 1 N/A SN-2008A 1 ACS/WFC ACCUM WFC1 F625W 4 none none none 1 N/A SN-2008A 2 ACS/WFC ACCUM WFC1 F625W none none none none 2 N/A SN-2008A 3 ACS/WFC ACCUM WFC1 F625W none none none none 2 N/A SN-2008A 4 ACS/WFC ACCUM WFC1 F555W none none none none 2 N/A SN-2008A 5 ACS/WFC ACCUM WFC1 F555W none none none none 2 N/A SN-2008A 6 ACS/WFC ACCUM WFC1 F555W 1 none none none 3 N/A SN-2008A 6 ACS/WFC ACCUM WFC1 F555W 2 none none none 3 N/A SN-2008A 6 ACS/WFC ACCUM WFC1 F555W 3 none none none 3 N/A SN-2008A 6 ACS/WFC ACCUM WFC1 F555W 4 none none none 3 N/A SN-2008A 7 ACS/WFC ACCUM WFC1 F775W 1 none none none 4 N/A SN-2008A 7 ACS/WFC ACCUM WFC1 F775W 2 none none none 4 N/A SN-2008A 7 ACS/WFC ACCUM WFC1 F775W 3 none none none 4 N/A SN-2008A 7 ACS/WFC ACCUM WFC1 F775W 4 none none none 4 N/A 11590( 7) - 23-Jun-2009 17:33:49 - [ 8] Visit: 03 Visit Requirements: GYRO MODE 2G; BETWEEN 15-JAN-2009:00:00:01 AND 31-MAR-2009:23:59:59 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 SN-2008A WFPC2 IMAGE PC1 F439W 1 500 S POS TARG -7, -8 ------------------------------------------------------------------------------------------------------------------------------------ 2 SN-2008A WFPC2 IMAGE PC1 F439W 1 500 S POS TARG -6.751, -7.751 ------------------------------------------------------------------------------------------------------------------------------------ 3 SN-2008A WFPC2 IMAGE PC1 F439W 1 500 S POS TARG -6.502, -7.502 ------------------------------------------------------------------------------------------------------------------------------------ 4 SN-2008A WFPC2 IMAGE PC1 F850LP 1 350 S POS TARG -6.502, -7.502 ------------------------------------------------------------------------------------------------------------------------------------ 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 | ------------------------------------------------------------------------------------------------------------------------------------ SN-2008A 1 WFPC2 IMAGE PC1 F439W none none none none 1 N/A SN-2008A 2 WFPC2 IMAGE PC1 F439W none none none none 1 N/A SN-2008A 3 WFPC2 IMAGE PC1 F439W none none none none 1 N/A SN-2008A 4 WFPC2 IMAGE PC1 F850LP none none none none 1 N/A 11590( 7) - 23-Jun-2009 17:33:49 - [ 9] Visit: 04 Visit Requirements: BETWEEN 01-JUN-2009:00:00:01 AND 31-AUG-2009:23:59:59 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 SN-2008A WFC3/IR MULTIAC IR F110W NSAMP=14, SAMP-SEQ=SPARS50 1 DEF POS TARG -0.835, -0.835 CUM ------------------------------------------------------------------------------------------------------------------------------------ 2 SN-2008A WFC3/IR MULTIAC IR F110W NSAMP=15, SAMP-SEQ=SPARS50 1 DEF POS TARG -0.321, -0.643 CUM ------------------------------------------------------------------------------------------------------------------------------------ 3 SN-2008A WFC3/IR MULTIAC IR F110W NSAMP=15, SAMP-SEQ=SPARS50 1 DEF POS TARG -0.514, -0.321 CUM ------------------------------------------------------------------------------------------------------------------------------------ 4 SN-2008A WFC3/IR MULTIAC IR F110W NSAMP=14, SAMP-SEQ=SPARS50 1 DEF POS TARG -1.028, -0.514 CUM ------------------------------------------------------------------------------------------------------------------------------------ 5 SN-2008A WFC3/IR MULTIAC IR F110W NSAMP=15, SAMP-SEQ=SPARS50 1 DEF PATTERN 2 5 CUM ------------------------------------------------------------------------------------------------------------------------------------ 6 SN-2008A WFC3/IR MULTIAC IR F110W NSAMP=15, SAMP-SEQ=SPARS50 1 DEF POS TARG 0.835, -0.835; CUM PATTERN 2 6 ------------------------------------------------------------------------------------------------------------------------------------ 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 | ------------------------------------------------------------------------------------------------------------------------------------ SN-2008A 1 WFC3/IR MULTIAC IR F110W none none none none 1 N/A CUM SN-2008A 2 WFC3/IR MULTIAC IR F110W none none none none 1 N/A CUM SN-2008A 3 WFC3/IR MULTIAC IR F110W none none none none 1 N/A CUM SN-2008A 4 WFC3/IR MULTIAC IR F110W none none none none 1 N/A CUM SN-2008A 5 WFC3/IR MULTIAC IR F110W 1 none none none 2 N/A CUM SN-2008A 5 WFC3/IR MULTIAC IR F110W 2 none none none 2 N/A CUM SN-2008A 5 WFC3/IR MULTIAC IR F110W 3 none none none 2 N/A CUM SN-2008A 5 WFC3/IR MULTIAC IR F110W 4 none none none 2 N/A CUM SN-2008A 6 WFC3/IR MULTIAC IR F110W 1 none none none 3 N/A CUM 11590( 7) - 23-Jun-2009 17:33:49 - [ 10] 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 | ------------------------------------------------------------------------------------------------------------------------------------ SN-2008A 6 WFC3/IR MULTIAC IR F110W 2 none none none 3 N/A CUM SN-2008A 6 WFC3/IR MULTIAC IR F110W 3 none none none 3 N/A CUM SN-2008A 6 WFC3/IR MULTIAC IR F110W 4 none none none 3 N/A CUM 11590( 7) - 23-Jun-2009 17:33:49 - [ 11] Summary Form for Proposal 11590 Item Used in this proposal ------------------------------------------------------------------------------------------------------------------------------------ Apertures IR, PC1, WFC1 ------------------------------------------------------------------------------------------------------------------------------------ Configurations ACS/WFC, WFC3/IR, WFPC2 ------------------------------------------------------------------------------------------------------------------------------------ Opmodes ACCUM, IMAGE, MULTIACCUM ------------------------------------------------------------------------------------------------------------------------------------ Optional Parameters NSAMP=14, NSAMP=15, SAMP-SEQ=SPARS50 ------------------------------------------------------------------------------------------------------------------------------------ Special Requirements BETWEEN 01-JUN-2009:00:00:01 AND 31-AUG-2009:23:59:59, BETWEEN 15-JAN-2009:00:00:01 AND 31-MAR-2009:23:59:59, GYRO MODE 2G, ORIENT 205D TO 295 D, PATTERN 1 1, PATTERN 1 6, PATTERN 1 7, PATTERN 2 5, PATTERN 2 6, POS TARG -0.321, -0.643, POS TARG -0.514, -0.321, POS TARG -0.835, -0.835, POS TARG -1.028, -0.514, POS TARG -6.502, -7.502, POS TARG -6.751, -7.751, POS TARG -7, -8, POS TARG 0.099, 0.107, POS TARG 0.198, 0.214, POS TARG 0.835, -0.835 ------------------------------------------------------------------------------------------------------------------------------------ Spectral Elements F110W, F439W, F555W, F622W, F625W, F775W, F791W, F850LP ------------------------------------------------------------------------------------------------------------------------------------ Target Names SN-2008A ------------------------------------------------------------------------------------------------------------------------------------