17603( 4) - 13-Feb-2024 22:57:55 - [ 1] HUBBLE SPACE TELESCOPE OBSERVING PROGRAM 17603 Version: 4 Check-in Time: 13-Feb-2024 22:57:55 STScI Edit Number: 0 Title Did the progenitor of the Type IIb SN2011dh actually have a binary companion? ------------------------------------------------------------------------------------ Type Cycle GO 31 ------------------------------------------------------------------------------------ Investigators Contact? PI: Dr. Justyn Robert Maund Royal Holloway, University of London Y ------------------------------------------------------------------------------------ Abstract The progenitors of Type IIb SNe retain a small amount of hydrogen (<0.1Msun), making them sensitive probes of the mass loss processes (stellar winds, interactions with binary companions) that affect the evolution of massive stars. SN 2011dh is one of the best observed SNe in the last 20 years, with a peculiar Yellow Supergiant progenitor detected in HST pre-explosion images. Since 2011, late-time UV imaging of the site of SN2011dh had revealed a constant UV-bright source that was assumed for the last 11 years to be the companion to the progenitor, responsible for its peculiar appearance. In 2023, observations of the host galaxy of SN2011dh have revealed that, in the time since the last multiwavelength observations in 2017, the UV brightness of SN2011dh was not constant but has plummeted! Here we propose a deep, multi-wavelength set of observations to probe whether a companion star is truly present, and eliminate other scenarios including the formation of new dust in the fading SN and the role of a light echo. ------------------------------------------------------------------------------------ Observations Description ------------------------ We require deep UV to near-infrared imaging of the site of SN2011dh. In order to capture the evolution of SN2011dh, we require an observation in the next 2 - 3 months (which has been implemented in the visit planner). Each observation, with each filter, is split into two subexposures with a dither offset. We are using the default 2-point line dither patterns for the UVIS and IR channels to allow for rejection of cosmic rays, hot pixels and blobs. We have grouped filters ([F657N and F336W], [F275W and F814W], [F555W, F125W and F160W]) to acquire exposures with alternating filters within the 2-point dither pattern so all observations can fit within the 5 orbit allocation. The pointing is centered on the position of SN2011dh, and we are using the 1k x 1k CTE subarray (for UVIS) to minimize readout time and the effects of CTE - for the IR image we are acquiring the full frame. ------------------------------------------------------------------------------------ 17603( 4) - 13-Feb-2024 22:57:55 - [ 2] TARGET LIST Fixed Targets ------------------------------------------------------------------------------------------------------------------------------------ Tar| Target | Target | Target |Coord | Radial | Flux data No | Name | Description | Position |Eqnx | Vel. | ------------------------------------------------------------------------------------------------------------------------------------ 1 SN-2011DH EXT-STAR, SUPERNOVA RA=13H30M5.1055S, J2000 V = 25.0 TYPE II DEC=+47D10'10.92" Reference Frame: Other: SIMBAD Extended: NO Comments: This object was generated by the targetselector and retrieved from the SIMBAD database. Epoch of Position RA proper motion (seconds of time/yr) DEC Proper Motion (arcsec/yr) Annual Parallax (arcsec) 2000 0.0 0.0 0.0 ------------------------------------------------------------------------------------------------------------------------------------ 17603( 4) - 13-Feb-2024 22:57:55 - [ 3] Patterns ------------------------------------------------------------------------------------------------------------------------------------ Pattern_Number: 1 Primary_Pattern Secondary_Pattern Pattern_Type WFC3-IR-DITHER-LINE Pattern_Purpose DITHER Number_Of_Points 2 Point_Spacing 0.636 Line_Spacing Coordinate_Frame POS-TARG Pattern_Orient 41.788 Angle_Between_Sides Center_Pattern NO ------------------------------------------------------------------------------------------------------------------------------------ Pattern_Number: 2 Primary_Pattern Secondary_Pattern Pattern_Type WFC3-UVIS-DITHER-LINE Pattern_Purpose DITHER Number_Of_Points 2 Point_Spacing 0.145 Line_Spacing Coordinate_Frame POS-TARG Pattern_Orient 46.84 Angle_Between_Sides Center_Pattern NO ------------------------------------------------------------------------------------------------------------------------------------ 17603( 4) - 13-Feb-2024 22:57:55 - [ 4] Visit: 01 Visit Requirements: BEFORE 30-APR-2024:00:00:00 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| (Total) | Requirements ------------------------------------------------------------------------------------------------------------------------------------ 1 SN-2011DH WFC3/UVI ACCUM UVIS2-C1K F657N FLASH=20 1 950 S PATTERN 2 1-2 S 1C-CTE see below (2145 S) ------------------------------------------------------------------------------------------------------------------------------------ 2 SN-2011DH WFC3/UVI ACCUM UVIS2-C1K F336W FLASH=20 1 1500 S S 1C-CTE see below (3250 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-2011DH 1 WFC3/UVI ACCUM UVIS2-C1 F657N 1 none none none 1 1075.0 S S K1C-CTE SN-2011DH 1 WFC3/UVI ACCUM UVIS2-C1 F657N 2 none none none 2 1070.0 S S K1C-CTE SN-2011DH 2 WFC3/UVI ACCUM UVIS2-C1 F336W 1 none none none 1 1625.0 S S K1C-CTE SN-2011DH 2 WFC3/UVI ACCUM UVIS2-C1 F336W 2 none none none 2 1625.0 S S K1C-CTE 17603( 4) - 13-Feb-2024 22:57:55 - [ 5] Visit: 02 Visit Requirements: BEFORE 30-APR-2024:00:00:00 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| (Total) | Requirements ------------------------------------------------------------------------------------------------------------------------------------ 1 SN-2011DH WFC3/UVI ACCUM UVIS2-C1K F275W FLASH=20 1 2100 S PATTERN 2 1-2 S 1C-CTE see below (4383 S) ------------------------------------------------------------------------------------------------------------------------------------ 2 SN-2011DH WFC3/UVI ACCUM UVIS2-C1K F814W FLASH=20 1 425 S S 1C-CTE see below (1033 S) ------------------------------------------------------------------------------------------------------------------------------------ 3 SN-2011DH WFC3/IR MULTIAC IR F160W SAMP-SEQ=SPARS50, NSAMP=11 1 DEF PATTERN 1 3-4 CUM (1005.874 S) ------------------------------------------------------------------------------------------------------------------------------------ 4 SN-2011DH WFC3/IR MULTIAC IR F125W SAMP-SEQ=SPARS50, NSAMP=9 1 DEF CUM (805.872 S) ------------------------------------------------------------------------------------------------------------------------------------ 5 SN-2011DH WFC3/UVI ACCUM UVIS2-C1K F555W FLASH=20 1 335 S (670 PATTERN 2 5 S 1C-CTE 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-2011DH 1 WFC3/UVI ACCUM UVIS2-C1 F275W 1 none none none 1 2194.0 S S K1C-CTE SN-2011DH 1 WFC3/UVI ACCUM UVIS2-C1 F275W 2 none none none 2 2189.0 S S K1C-CTE SN-2011DH 2 WFC3/UVI ACCUM UVIS2-C1 F814W 1 none none none 1 519.0 S S K1C-CTE SN-2011DH 2 WFC3/UVI ACCUM UVIS2-C1 F814W 2 none none none 2 514.0 S S K1C-CTE SN-2011DH 3 WFC3/IR MULTIAC IR F160W 1 none none none 3 N/A CUM SN-2011DH 3 WFC3/IR MULTIAC IR F160W 2 none none none 3 N/A CUM SN-2011DH 4 WFC3/IR MULTIAC IR F125W 1 none none none 3 N/A CUM SN-2011DH 4 WFC3/IR MULTIAC IR F125W 2 none none none 3 N/A CUM 17603( 4) - 13-Feb-2024 22:57:55 - [ 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-2011DH 5 WFC3/UVI ACCUM UVIS2-C1 F555W 1 none none none 3 N/A S K1C-CTE SN-2011DH 5 WFC3/UVI ACCUM UVIS2-C1 F555W 2 none none none 3 N/A S K1C-CTE 17603( 4) - 13-Feb-2024 22:57:55 - [ 7] Summary Form for Proposal 17603 Item Used in this proposal ------------------------------------------------------------------------------------------------------------------------------------ Apertures IR, UVIS2-C1K1C-CTE ------------------------------------------------------------------------------------------------------------------------------------ Configurations WFC3/IR, WFC3/UVIS ------------------------------------------------------------------------------------------------------------------------------------ Opmodes ACCUM, MULTIACCUM ------------------------------------------------------------------------------------------------------------------------------------ Optional Parameters FLASH=20, NSAMP=11, NSAMP=9, SAMP-SEQ=SPARS50 ------------------------------------------------------------------------------------------------------------------------------------ Special Requirements BEFORE 30-APR-2024:00:00:00, PATTERN 1 3-4, PATTERN 2 1-2, PATTERN 2 5 ------------------------------------------------------------------------------------------------------------------------------------ Spectral Elements F125W, F160W, F275W, F336W, F555W, F657N, F814W ------------------------------------------------------------------------------------------------------------------------------------ Target Names SN-2011DH ------------------------------------------------------------------------------------------------------------------------------------