11646( 6) - 30-Jun-2009 17:14:28 - [ 1] HUBBLE SPACE TELESCOPE OBSERVING PROGRAM 11646 Version: 6 Check-in Time: 30-Jun-2009 17:14:28 STScI Edit Number: 3 Title Light Echoes as Probes of Supernova Type Ia Environments ------------------------------------------------------------------------------------ Type Cycle GO 17 ------------------------------------------------------------------------------------ Investigators Contact? PI: Dr. Arlin Crotts Columbia University in the City of New York CoI: Dr. Ben E. Sugerman Goucher College N ------------------------------------------------------------------------------------ Abstract Environmental factors of Type Ia supernovae are key in understanding their nature, lightcurve evolution, and utility as cosmological standard candles. The progenitor ages (and many other properties) are bimodal, differing by roughly an order of magnitude. Is this reflected as well in the differences in their immediate surroundings in terms of gas and dust? The most powerful and direct way to address this issue is by imaging the reflected light from the dust itself via a light echo. In order for this approach to work, however, one must start imaging the vicinity of the supernova frequently and soon after the explosion is seen. We propose to maintain the imaging sequences crucial for understanding the three-dimensional dust distribution of two recent and key Type Ia supernovae, in a timely manner that will prevent otherwise significant holes in our knowledge. These observations are likely to be important in determining if the interstellar versus the circumstellar environments are more important in determining the appearance of Type Ia explosions, and thereby offer a clue as to the poorly-understood mass-loss history of SN Ia progenitors. JUSTIFICATION FOR VISIT TIME CONSTRAINTS: We have requested "Before" conditions ------------------------------------------------------------------------------------ Observations Description ------------------------ Our proposed exposure times and the expected signals to be returned by HST are reliably anticipated from previous exposures of earlier incarnations of these sources using imagers other than WFC3/UVIS. For SN 2006X our main priority will be to best determine the new echo geometry, hence we will use much of the 1 orbit requested for F555W observations (about 970s) that will define the echo locus most efficiently and match previous observations. We will also devote about 970s to F475W and 270s for F775W to provide sensitivity to any color change and to provide a reasonable match to previous HST/WFPC2 observations. For SN 1998bu we will make similar observations, but go deeper in the "echo geometry band" (F606W) and also include a deep exposure in F658N to capture optimally any non-echo CSM signal and provide an H-alpha line strength. JUSTIFICATION FOR VISIT TIMING REQUIREMENTS: We have requested a "Before" condition in the Visit Timing Requirements due to the rapidly changing nature of these targets' evolution and the unanticipated 11646( 6) - 30-Jun-2009 17:14:28 - [ 2] extension of the interval since the previous observations, in light of Servicing Mission 4. This is particularly critical in the case of SN 2006X (Target 1); there was a rapid series of HST images taken in May 2006 - January 2008, followed by an 18+ month delay. This time gap must be closed as soon as possible. The same argument applies to SN 1998bu (Target 2) but is less critical. There were five relevant epochs of HST imaging prior to January 2006, followed by a 42+ month delay. Closing these gaps as soon as possible increases the likelihood of maintaining adequate light echo coverage to 3-dimensionally map the surrounding material commensurate with the angular resolution of HST, which cannot be retrieved from later observations. Please, if at all possible, try to implement these Before conditions. Of course, the observations will still be of great value even if this is impossible. Real Time Justification ----------------------- Calibration Justification ------------------------- Additional Comments ------------------- ------------------------------------------------------------------------------------ 11646( 6) - 30-Jun-2009 17:14:28 - [ 3] TARGET LIST Fixed Targets ------------------------------------------------------------------------------------------------------------------------------------ Tar| Target | Target | Target |Coord | Radial | Flux data No | Name | Description | Position |Eqnx | Vel. | ------------------------------------------------------------------------------------------------------------------------------------ 1 SN2006X EXT-STAR, SUPERNOVA RA=12H22M53.8800S +/- 0.1", J2000 V = 23 TYPE IA DEC=+15D48'31.90" +/- 0.1" Reference Frame: ICRS Comments: ------------------------------------------------------------------------------------------------------------------------------------ 2 SN1998BU EXT-STAR, SUPERNOVA RA=10H46M46.0900S +/- 0.1", J2000 V = 23 TYPE IA DEC=+11D50'7.00" +/- 0.1" Reference Frame: ICRS Comments: ------------------------------------------------------------------------------------------------------------------------------------ 11646( 6) - 30-Jun-2009 17:14:28 - [ 4] Visit: 01 Visit Requirements: BEFORE 15-NOV-2009:11:59:00 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 SN2006X WFC3/UVI ACCUM UVIS1-FIX F775W CR-SPLIT=NO 1 180 S GS ACQ SCENARIO SINGLE S ------------------------------------------------------------------------------------------------------------------------------------ 2 SN2006X WFC3/UVI ACCUM UVIS1-FIX F775W CR-SPLIT=NO 1 90 S S ------------------------------------------------------------------------------------------------------------------------------------ 3 SN2006X WFC3/UVI ACCUM UVIS1-FIX F475W CR-SPLIT=NO 1 670 S S ------------------------------------------------------------------------------------------------------------------------------------ 4 SN2006X WFC3/UVI ACCUM UVIS1-FIX F475W CR-SPLIT=NO 1 300 S S ------------------------------------------------------------------------------------------------------------------------------------ 5 SN2006X WFC3/UVI ACCUM UVIS1-FIX F555W CR-SPLIT=NO 1 670 S S ------------------------------------------------------------------------------------------------------------------------------------ 6 SN2006X WFC3/UVI ACCUM UVIS1-FIX F555W CR-SPLIT=NO 1 300 S 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 | ------------------------------------------------------------------------------------------------------------------------------------ SN2006X 1 WFC3/UVI ACCUM UVIS1-FI F775W none none none none 1 N/A S X SN2006X 2 WFC3/UVI ACCUM UVIS1-FI F775W none none none none 1 N/A S X SN2006X 3 WFC3/UVI ACCUM UVIS1-FI F475W none none none none 1 N/A S X SN2006X 4 WFC3/UVI ACCUM UVIS1-FI F475W none none none none 1 N/A S X SN2006X 5 WFC3/UVI ACCUM UVIS1-FI F555W none none none none 1 N/A S X SN2006X 6 WFC3/UVI ACCUM UVIS1-FI F555W none none none none 1 N/A S X 11646( 6) - 30-Jun-2009 17:14:28 - [ 5] Visit: 02 Visit Requirements: BEFORE 15-NOV-2009:11:59:00 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 SN1998BU WFC3/UVI ACCUM UVIS1-FIX F814W CR-SPLIT=2 1 350 S S ------------------------------------------------------------------------------------------------------------------------------------ 2 SN1998BU WFC3/UVI ACCUM UVIS1-FIX F606W CR-SPLIT=3 1 2010 S S ------------------------------------------------------------------------------------------------------------------------------------ 3 SN1998BU WFC3/UVI ACCUM UVIS1-FIX F475W 1 500 S S ------------------------------------------------------------------------------------------------------------------------------------ 4 SN1998BU WFC3/UVI ACCUM UVIS1-FIX F658N CR-SPLIT=3 1 2010 S 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 | ------------------------------------------------------------------------------------------------------------------------------------ SN1998BU 1 WFC3/UVI ACCUM UVIS1-FI F814W none none none 1 1 N/A S X SN1998BU 1 WFC3/UVI ACCUM UVIS1-FI F814W none none none 2 1 N/A S X SN1998BU 2 WFC3/UVI ACCUM UVIS1-FI F606W none none none 1 1 N/A S X SN1998BU 2 WFC3/UVI ACCUM UVIS1-FI F606W none none none 2 1 N/A S X SN1998BU 2 WFC3/UVI ACCUM UVIS1-FI F606W none none none 3 1 N/A S X SN1998BU 3 WFC3/UVI ACCUM UVIS1-FI F475W none none none 1 2 N/A S X SN1998BU 3 WFC3/UVI ACCUM UVIS1-FI F475W none none none 2 2 N/A S X SN1998BU 4 WFC3/UVI ACCUM UVIS1-FI F658N none none none 1 2 N/A S X SN1998BU 4 WFC3/UVI ACCUM UVIS1-FI F658N none none none 2 2 N/A S X SN1998BU 4 WFC3/UVI ACCUM UVIS1-FI F658N none none none 3 2 N/A S X 11646( 6) - 30-Jun-2009 17:14:28 - [ 6] Summary Form for Proposal 11646 Item Used in this proposal ------------------------------------------------------------------------------------------------------------------------------------ Apertures UVIS1-FIX ------------------------------------------------------------------------------------------------------------------------------------ Configurations WFC3/UVIS ------------------------------------------------------------------------------------------------------------------------------------ Opmodes ACCUM ------------------------------------------------------------------------------------------------------------------------------------ Optional Parameters CR-SPLIT=2, CR-SPLIT=3, CR-SPLIT=NO ------------------------------------------------------------------------------------------------------------------------------------ Special Requirements BEFORE 15-NOV-2009:11:59:00, GS ACQ SCENARIO SINGLE ------------------------------------------------------------------------------------------------------------------------------------ Spectral Elements F475W, F555W, F606W, F658N, F775W, F814W ------------------------------------------------------------------------------------------------------------------------------------ Target Names SN1998BU, SN2006X ------------------------------------------------------------------------------------------------------------------------------------