13648( 3) - 31-Jul-2014 15:53:08 - [ 1] HUBBLE SPACE TELESCOPE OBSERVING PROGRAM 13648 Version: 3 Check-in Time: 31-Jul-2014 15:53:08 STScI Edit Number: 0 Title Uncovering the Putative B-Star Binary Companion of the SN 1993J Progenitor ------------------------------------------------------------------------------------ Type Cycle GO 22 ------------------------------------------------------------------------------------ Investigators Contact? PI: Dr. Ori Dosovitz Fox University of California - Berkeley Y CoI: Ms. Azalee K. Bostroem Space Telescope Science Institute N CoI: Dr. Schuyler D. Van Dyk California Institute of Technology N CoI: Prof. Alex V. Filippenko University of California - Berkeley N CoI: Dr. Thomas Matheson National Optical Astronomy Observatory, N AURA CoI: Dr. Poonam Chandra Royal Military College of Canada N CoI: Dr. Vikram Dwarkadas University of Chicago N CoI: Dr. Nathan Smith University of Arizona N CoI: Prof. Claes Fransson Stockholm University N ------------------------------------------------------------------------------------ Abstract The stripped-envelope Type IIb supernova (SN IIb) is a unique subclass of core-collapse explosions that result when a massive star loses most, but not all, of its outer envelope. Theoretical models suggest progenitor systems consist of low-mass stars that lose their envelopes during mass transfer to a binary companion, which becomes UV bright in the process. Although four stripped-envelope supernovae have progenitor stars identified in pre-explosion images, not a single progenitor companion star has been directly detected to date. In other words, the Type IIb progenitor system remains observationally unconfirmed. The nearby Type IIb SN 1993J in M81, at a distance of only 3.6 Mpc, offers one of the best opportunities to detect the putative companion and test the progenitor model. Indeed, evidence has been mounting over the past decade for a hot companion, but the dominating SN flux and contamination from nearby stars has made a confirmation difficult. In 2012, our team obtained HST/COS spectra and detected a far-UV (FUV) excess flux consistent with a hot B-star. This spectrum, however, is limited by a low signal-to-noise ratio and poor spatial resolution. Now that the SN has sufficiently faded, we propose FUV and NUV imaging of SN 1993J and the surrounding stars to disentangle the source of the FUV excess flux once and for all. Coinciding with Cycle 22's UV initiative, we can shed light on the binary nature of Type IIb progenitors in just 3 orbits. ------------------------------------------------------------------------------------ Observations Description ------------------------ WFC3: - Use the C512C subarray - Near amp C - mitigate CTE - low flat field gradient - 512 pix = 20 arcsec - plenty of room to dither and get all of surrounding stars - short readout --> get almost all of our planned exposure time 13648( 3) - 31-Jul-2014 15:53:08 - [ 2] - amp C has ~20 droplet, but we arent going to worry about the droplets - Don't have to use POSTARGs to put target near amplifier - EXPTIME (actual/ planned): - F218W - 3000s/3000s - F275 - 2260s/2300s - F336W - 640s/700s - FLASH = 9 - Based on 12531 observations, background is ~2.5, we want 12 e-/pix --> FLASH of 9 e-/pix - 1 WFC3 visit: - putting all WFC3 observations in one 2 orbit visit. We want everything relatively close in time anyways, why not? - 4 pt box dither - sub pixel dither to maximize PSF sampling and therefore spatial sampling - remove CR and hot pixels ACS: - ETC Calc for binary companion: http://etc.stsci.edu/etc/results/ACS.im.573826/ - F140LP - remove airglow lines - EXPTIME (actual/planned) = 3150s/3000s - Use SBC aperture ------------------------------------------------------------------------------------ 13648( 3) - 31-Jul-2014 15:53:08 - [ 3] TARGET LIST Fixed Targets ------------------------------------------------------------------------------------------------------------------------------------ Tar| Target | Target | Target |Coord | Radial | Flux data No | Name | Description | Position |Eqnx | Vel. | ------------------------------------------------------------------------------------------------------------------------------------ 1 SN-1993J EXT-STAR, SUPERNOVA RA=09H55M24.9500S, J2000 V = 22.9 DEC=+69D01'13.40" Reference Frame: Other: NED Comments: This object was generated by the targetselector and retrieved from the NED database. ------------------------------------------------------------------------------------------------------------------------------------ 13648( 3) - 31-Jul-2014 15:53:08 - [ 4] Patterns ------------------------------------------------------------------------------------------------------------------------------------ Pattern_Number: 5 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 ------------------------------------------------------------------------------------------------------------------------------------ 13648( 3) - 31-Jul-2014 15:53:08 - [ 5] Visit: 01 Visit Requirements: On Hold Comments: Additional Comments: Y POS-TARG = -4 for the WFC3 exposures to mitigate CTE while staying > 5 arcsec away from chip edge to avoid flat field artifacts Exposures ------------------------------------------------------------------------------------------------------------------------------------ Exp | Target | Instr | Oper. | Aper |Spectral|Central| Optional |Num| Time | Special Num | Name | Config | Mode | or FOV |Element |Waveln.| Parameters |Exp| (Total) | Requirements ------------------------------------------------------------------------------------------------------------------------------------ 1 SN-1993J WFC3/UVI ACCUM UVIS2-C51 F218W FLASH=12 1 750 S POS TARG null, -4; S 2C-SUB (3000 S) PATTERN 5 1 ------------------------------------------------------------------------------------------------------------------------------------ 2 SN-1993J WFC3/UVI ACCUM UVIS2-C51 F275W FLASH=12 1 565 S POS TARG null, -4; S 2C-SUB (2260 S) PATTERN 5 2 ------------------------------------------------------------------------------------------------------------------------------------ 3 SN-1993J WFC3/UVI ACCUM UVIS2-C51 F336W FLASH=12 1 160 S (640 POS TARG null, -4; S 2C-SUB S) PATTERN 5 3 ------------------------------------------------------------------------------------------------------------------------------------ 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-1993J 1 WFC3/UVI ACCUM UVIS2-C5 F218W 1 none none none 1 N/A S 12C-SUB SN-1993J 1 WFC3/UVI ACCUM UVIS2-C5 F218W 2 none none none 1 N/A S 12C-SUB SN-1993J 1 WFC3/UVI ACCUM UVIS2-C5 F218W 3 none none none 1 N/A S 12C-SUB SN-1993J 1 WFC3/UVI ACCUM UVIS2-C5 F218W 4 none none none 1 N/A S 12C-SUB SN-1993J 2 WFC3/UVI ACCUM UVIS2-C5 F275W 1 none none none 2 N/A S 12C-SUB SN-1993J 2 WFC3/UVI ACCUM UVIS2-C5 F275W 2 none none none 2 N/A S 12C-SUB SN-1993J 2 WFC3/UVI ACCUM UVIS2-C5 F275W 3 none none none 2 N/A S 12C-SUB SN-1993J 2 WFC3/UVI ACCUM UVIS2-C5 F275W 4 none none none 2 N/A S 12C-SUB SN-1993J 3 WFC3/UVI ACCUM UVIS2-C5 F336W 1 none none none 2 N/A S 12C-SUB SN-1993J 3 WFC3/UVI ACCUM UVIS2-C5 F336W 2 none none none 2 N/A S 12C-SUB SN-1993J 3 WFC3/UVI ACCUM UVIS2-C5 F336W 3 none none none 2 N/A S 12C-SUB SN-1993J 3 WFC3/UVI ACCUM UVIS2-C5 F336W 4 none none none 2 N/A S 12C-SUB 13648( 3) - 31-Jul-2014 15:53:08 - [ 6] Visit: 02 Visit Requirements: GROUP 02, 01 WITHIN 30D 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| (Total) | Requirements ------------------------------------------------------------------------------------------------------------------------------------ 1 SN-1993J ACS/SBC ACCUM SBC F140LP 1 3150 S (3150 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 | ------------------------------------------------------------------------------------------------------------------------------------ SN-1993J 1 ACS/SBC ACCUM SBC F140LP none none none none 1 N/A 13648( 3) - 31-Jul-2014 15:53:08 - [ 7] Summary Form for Proposal 13648 Item Used in this proposal ------------------------------------------------------------------------------------------------------------------------------------ Apertures SBC, UVIS2-C512C-SUB ------------------------------------------------------------------------------------------------------------------------------------ Configurations ACS/SBC, WFC3/UVIS ------------------------------------------------------------------------------------------------------------------------------------ Opmodes ACCUM ------------------------------------------------------------------------------------------------------------------------------------ Optional Parameters FLASH=12 ------------------------------------------------------------------------------------------------------------------------------------ Special Requirements GROUP 02, 01 WITHIN 30D, PATTERN 5 1, PATTERN 5 2, PATTERN 5 3, POS TARG null, -4 ------------------------------------------------------------------------------------------------------------------------------------ Spectral Elements F140LP, F218W, F275W, F336W ------------------------------------------------------------------------------------------------------------------------------------ Target Names SN-1993J ------------------------------------------------------------------------------------------------------------------------------------