16903( 2) - 23-Dec-2021 14:10:59 - [ 1] HUBBLE SPACE TELESCOPE OBSERVING PROGRAM 16903 Version: 2 Check-in Time: 23-Dec-2021 14:10:59 STScI Edit Number: 0 Title Late-time imaging of Type Ia supernova SN 2017erp ------------------------------------------------------------------------------------ Type Cycle GO/DD 29 ------------------------------------------------------------------------------------ Investigators Contact? PI: Dr. Or Graur University of Portsmouth Y CoI: Dr. Saurabh W. Jha Rutgers the State University of New Jersey N CoI: Dr. Adam Riess The Johns Hopkins University N CoI: Dr. Wenlong Yuan The Johns Hopkins University N ------------------------------------------------------------------------------------ Abstract We ask for 3 WFC3/UVIS orbits to obtain F438W, F555W, and F814W images of the location of the Type Ia supernova (SN) 2017erp. We recently discovered a point source at the location of the SN in WFC3/IR observations taken during Feb. and Sep. 2021. We rule out the SN itself or a light echo. Instead, the object is consistent with a subgiant or red giant at a temperature of ~5000 K, but with an abnormally high luminosity of ~33, 000 Solar luminosities. It may be a clump of red giants or a globular cluster at or behind the location of the SN. No other SN Ia has ever been directly associated with such a stellar group. A more exciting possibility is that this object is the shock-heated surviving companion of SN 2017erp's progenitor. If so, this will be the first-ever detection of a surviving companion in a normal SN Ia. It would also provide direct evidence of the "single degenerate" channel whereby a white dwarf explodes after accreting matter from a main sequence or evolved star. WFC3/UVIS has a higher resolution than WFC3/IR, which will allow us to precisely test the object's coincidence with the SN and determine whether it is resolved or not. The images will also flesh out the object's spectral energy distribution, for a more accurate classification, temperature, and luminosity. We ask for DD time so that these observations will be scheduled during 3-10 January 2022 or 14-28 February 2022, when one last infrared visit to this field is planned. By obtaining optical and infrared images at the same time, we will gain a complete snapshot of the object at a single moment in time, providing a baseline for comparison with any future observations to test the object's variability. ------------------------------------------------------------------------------------ Observations Description ------------------------ The goal of this program is to obtain deep, clean images of the location of the Type Ia supernova 2017erp in F438W, F555W, and F814W. To that end, each orbit is devoted to one filter using a WFC3-UVIS-DITHER-BOX pattern. A critical aspect of this program is that it be carried out together with, or as close as possible to, vist 14 from program GO-16250 (the last visit to NGC 5861 in that program). That visit will provide F110W and F160W observations of the same location. We ask that our program be scheduled within +/- 2 days of GO-16250 visit 14 (the last visit to NGC 5861). Ideally, our program and GO-16250 visit 14 would be carried out together, as if they were one combined visit. 16903( 2) - 23-Dec-2021 14:10:59 - [ 2] ------------------------------------------------------------------------------------ 16903( 2) - 23-Dec-2021 14:10:59 - [ 3] TARGET LIST Fixed Targets ------------------------------------------------------------------------------------------------------------------------------------ Tar| Target | Target | Target |Coord | Radial | Flux data No | Name | Description | Position |Eqnx | Vel. | ------------------------------------------------------------------------------------------------------------------------------------ 1 SN-2017ERP EXT-STAR, SUPERNOVA RA=15H09M14.8100S, J2000 V = 25 DEC=-11D20'3.20" Reference Frame: Other: SIMBAD 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) 2015.5 0.0 0.0 0.0 ------------------------------------------------------------------------------------------------------------------------------------ 16903( 2) - 23-Dec-2021 14:10:59 - [ 4] Patterns ------------------------------------------------------------------------------------------------------------------------------------ Pattern_Number: 1 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 ------------------------------------------------------------------------------------------------------------------------------------ 16903( 2) - 23-Dec-2021 14:10:59 - [ 5] 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-2017ERP WFC3/UVI ACCUM UVIS1 F438W FLASH=12 1 575 S PATTERN 1 1 S (2300 S) ------------------------------------------------------------------------------------------------------------------------------------ 2 SN-2017ERP WFC3/UVI ACCUM UVIS1 F555W FLASH=1 1 575 S PATTERN 1 2 S (2300 S) ------------------------------------------------------------------------------------------------------------------------------------ 3 SN-2017ERP WFC3/UVI ACCUM UVIS1 F814W FLASH=4 1 575 S PATTERN 1 3 S (2300 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-2017ERP 1 WFC3/UVI ACCUM UVIS1 F438W 1 none none none 1 N/A S SN-2017ERP 1 WFC3/UVI ACCUM UVIS1 F438W 2 none none none 1 N/A S SN-2017ERP 1 WFC3/UVI ACCUM UVIS1 F438W 3 none none none 1 N/A S SN-2017ERP 1 WFC3/UVI ACCUM UVIS1 F438W 4 none none none 1 N/A S SN-2017ERP 2 WFC3/UVI ACCUM UVIS1 F555W 1 none none none 2 N/A S SN-2017ERP 2 WFC3/UVI ACCUM UVIS1 F555W 2 none none none 2 N/A S SN-2017ERP 2 WFC3/UVI ACCUM UVIS1 F555W 3 none none none 2 N/A S SN-2017ERP 2 WFC3/UVI ACCUM UVIS1 F555W 4 none none none 2 N/A S SN-2017ERP 3 WFC3/UVI ACCUM UVIS1 F814W 1 none none none 3 N/A S SN-2017ERP 3 WFC3/UVI ACCUM UVIS1 F814W 2 none none none 3 N/A S SN-2017ERP 3 WFC3/UVI ACCUM UVIS1 F814W 3 none none none 3 N/A S SN-2017ERP 3 WFC3/UVI ACCUM UVIS1 F814W 4 none none none 3 N/A S 16903( 2) - 23-Dec-2021 14:10:59 - [ 6] Summary Form for Proposal 16903 Item Used in this proposal ------------------------------------------------------------------------------------------------------------------------------------ Apertures UVIS1 ------------------------------------------------------------------------------------------------------------------------------------ Configurations WFC3/UVIS ------------------------------------------------------------------------------------------------------------------------------------ Opmodes ACCUM ------------------------------------------------------------------------------------------------------------------------------------ Optional Parameters FLASH=1, FLASH=12, FLASH=4 ------------------------------------------------------------------------------------------------------------------------------------ Special Requirements PATTERN 1 1, PATTERN 1 2, PATTERN 1 3 ------------------------------------------------------------------------------------------------------------------------------------ Spectral Elements F438W, F555W, F814W ------------------------------------------------------------------------------------------------------------------------------------ Target Names SN-2017ERP ------------------------------------------------------------------------------------------------------------------------------------