14763( 2) - 11-Jul-2016 13:43:50 - [ 1] HUBBLE SPACE TELESCOPE OBSERVING PROGRAM 14763 Version: 2 Check-in Time: 11-Jul-2016 13:43:50 STScI Edit Number: 0 Title Exploring the source of the late-time brightness of SN 2011dh ------------------------------------------------------------------------------------ Type Cycle GO 24 ------------------------------------------------------------------------------------ Investigators Contact? PI: Dr. Justyn Robert Maund University of Sheffield Y ------------------------------------------------------------------------------------ Abstract Late-time HST broad-band photometric observations of SN 2011dh in 2014 and 2016 have shown that, rather than continuing to decline in brightness, the light curve is flattening off. The reason for this is unknown, but could be due to "freeze-out" in the ejecta, the onset of interaction between the ejecta and a new dense circumstellar medium, the presence of a light echo or, even, the presence of a binary companion being slowly revealed. Scenarios involving the onset of interaction between the ejecta and a distant circumstellar medium and the presence of a light echo in a dust shell around the SN, all depend directly on the mass loss history of the Yellow Supergiant progenitor. We propose a series of broad and narrow band observations of SN 2011dh to test each of the possible scenarios, and place constraints on the current properties of the ejecta of this SN and the mass loss history of the star that exploded. Only HST is capable of providing the combination of spatial resolution and depth at UV and optical wavelengths that will be critical to making precise photometric measurements of SN 2011dh. ------------------------------------------------------------------------------------ Observations Description ------------------------ The aim of this program is to acquire a series of broad and narrow band photometric observations of the fading Type IIb SN 2011dh. We aim to reach F336W~25.5, F555W~25.5 and F814W ~24.5 @ S/N=3 and 0.5 *10^(-18) ergs s^-1 cm^-2 A^-1 in the F631N and F657N bands, respectively. The observations in each filter will only require a single cr-split with a dither offset to enable rejection of hotpixels (and other detector artifacts) and cosmic rays, but resampling of the PSF is not required. ------------------------------------------------------------------------------------ 14763( 2) - 11-Jul-2016 13:43:50 - [ 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 = 25.5 +/- 0.1 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. ------------------------------------------------------------------------------------------------------------------------------------ 14763( 2) - 11-Jul-2016 13:43:50 - [ 3] Patterns ------------------------------------------------------------------------------------------------------------------------------------ Pattern_Number: 1 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 ------------------------------------------------------------------------------------------------------------------------------------ 14763( 2) - 11-Jul-2016 13:43:50 - [ 4] Visit: 01 Visit Requirements: 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-C51 F336W FLASH=12 1 1010 S PATTERN 1 1 S 2C-SUB (2020 S) ------------------------------------------------------------------------------------------------------------------------------------ 2 SN-2011DH WFC3/UVI ACCUM UVIS2-C51 F555W FLASH=2 1 400 S (800 PATTERN 1 2 S 2C-SUB S) ------------------------------------------------------------------------------------------------------------------------------------ 3 SN-2011DH WFC3/UVI ACCUM UVIS2-C51 F814W FLASH=2 1 450 S (900 PATTERN 1 3-5 S 2C-SUB S) ------------------------------------------------------------------------------------------------------------------------------------ 4 SN-2011DH WFC3/UVI ACCUM UVIS2-C51 F631N FLASH=8 1 1460 S S 2C-SUB (2920 S) ------------------------------------------------------------------------------------------------------------------------------------ 5 SN-2011DH WFC3/UVI ACCUM UVIS2-C51 F657N FLASH=8 1 1060 S S 2C-SUB (2120 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-C5 F336W 1 none none none 1 N/A S 12C-SUB SN-2011DH 1 WFC3/UVI ACCUM UVIS2-C5 F336W 2 none none none 1 N/A S 12C-SUB SN-2011DH 2 WFC3/UVI ACCUM UVIS2-C5 F555W 1 none none none 1 N/A S 12C-SUB SN-2011DH 2 WFC3/UVI ACCUM UVIS2-C5 F555W 2 none none none 1 N/A S 12C-SUB SN-2011DH 3 WFC3/UVI ACCUM UVIS2-C5 F814W 1 none none none 2 N/A S 12C-SUB SN-2011DH 3 WFC3/UVI ACCUM UVIS2-C5 F814W 2 none none none 3 N/A S 12C-SUB SN-2011DH 4 WFC3/UVI ACCUM UVIS2-C5 F631N 1 none none none 2 N/A S 12C-SUB SN-2011DH 4 WFC3/UVI ACCUM UVIS2-C5 F631N 2 none none none 3 N/A S 12C-SUB SN-2011DH 5 WFC3/UVI ACCUM UVIS2-C5 F657N 1 none none none 2 N/A S 12C-SUB SN-2011DH 5 WFC3/UVI ACCUM UVIS2-C5 F657N 2 none none none 3 N/A S 12C-SUB 14763( 2) - 11-Jul-2016 13:43:50 - [ 5] Summary Form for Proposal 14763 Item Used in this proposal ------------------------------------------------------------------------------------------------------------------------------------ Apertures UVIS2-C512C-SUB ------------------------------------------------------------------------------------------------------------------------------------ Configurations WFC3/UVIS ------------------------------------------------------------------------------------------------------------------------------------ Opmodes ACCUM ------------------------------------------------------------------------------------------------------------------------------------ Optional Parameters FLASH=12, FLASH=2, FLASH=8 ------------------------------------------------------------------------------------------------------------------------------------ Special Requirements PATTERN 1 1, PATTERN 1 2, PATTERN 1 3-5 ------------------------------------------------------------------------------------------------------------------------------------ Spectral Elements F336W, F555W, F631N, F657N, F814W ------------------------------------------------------------------------------------------------------------------------------------ Target Names SN-2011DH ------------------------------------------------------------------------------------------------------------------------------------