16768( 7) - 10-Jan-2022 20:12:03 - [ 1] HUBBLE SPACE TELESCOPE OBSERVING PROGRAM 16768 Version: 7 Check-in Time: 10-Jan-2022 20:12:03 STScI Edit Number: 5 Title Supernova 2020wnt: a pair-instability explosion in our backyard? ------------------------------------------------------------------------------------ Type Cycle GO 29 ------------------------------------------------------------------------------------ Investigators Contact? PI: Dr. Samaporn Tinyanont University of California - Santa Cruz Y CoI: Prof. Ryan Foley University of California - Santa Cruz N CoI: Kirsty Taggart University of California - Santa Cruz N CoI: Dr. Lin Yan California Institute of Technology N CoI: Dr. Ragnhild Lunnan Stockholm University N ------------------------------------------------------------------------------------ Abstract We propose for one orbit of WFC3 UVIS/IR imaging, and one non-disruptive ToO orbit of WFC3 IR grism spectroscopy of a nearby superluminous supernova (SLSN) 2020wnt to discern whether it is a pair-instability (PI) SN. PISNe are the theoretical death of a 140-260 solar mass stars, and they may be a dominant contributor to nucleosynthesis in the early universe. A direct observation of a bona fide PISN does not yet exist in the literature. SN 2020wnt is the best candidate for a PISN yet discovered. It has a long rise from a large ejecta mass (~60 Msun) to a peak luminosity of -20.5 mags; both consistent with some PISN models. The light curve declines post-maximum with a rate of 0.01 mag/day, consistent with the radioactive decay of Co-56. Lastly, latest near-IR spectrum shows shows features associated with Fe-group elements. These features point to an explosion that produces a copious amount of nickel, like a PISN. Our imaging observations will (i) determine whether the SN is still bright enough for the grism observations and (ii) probe the host properties local to the SN site. If the SN is brighter than 22 mags in the F140W filter, we will trigger a non-disruptive ToO to obtain grism spectroscopy. The particular lines we aim to observe are the [S I], [Si I] and [Fe II] line complexes around 1.1, 1.25, and 1.6 micron. The nebular spectrum will measure the nucleosynthetic yield of the SN, and unambiguously determine whether SN 2020wnt is a PISN or other more common deaths of a massive star. ------------------------------------------------------------------------------------ Observations Description ------------------------ We plan to observe SN 2020wnt in two epochs. The first epoch contains one orbit and focuses on imaging the SN and the host using WFC3 UVIS and IR with the F275W, F475W, F110W, F140W, and F160W. For the second epoch, we observe SN 2020wnt with the WFC3 IR Grisms. We will obtain direct imaging in the F105W and F140W filters. Then we will observe the source with both the G102 and G141 grisms. ------------------------------------------------------------------------------------ 16768( 7) - 10-Jan-2022 20:12:03 - [ 2] TARGET LIST Fixed Targets ------------------------------------------------------------------------------------------------------------------------------------ Tar| Target | Target | Target |Coord | Radial | Flux data No | Name | Description | Position |Eqnx | Vel. | ------------------------------------------------------------------------------------------------------------------------------------ 1 SN2020WNT EXT-STAR, SUPERNOVA RA=03H46M37.9500S, J2000 z = 22 AB mag DEC=+43D13'45.30" Reference Frame: ICRS Extended: NO ------------------------------------------------------------------------------------------------------------------------------------ 16768( 7) - 10-Jan-2022 20:12:03 - [ 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 ------------------------------------------------------------------------------------------------------------------------------------ 16768( 7) - 10-Jan-2022 20:12:03 - [ 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 SN2020WNT WFC3/IR MULTIAC IRSUB512 F160W NSAMP=6, SAMP-SEQ=SPARS25 1 DEF PATTERN 1 1-3 CUM (230.919 S) ------------------------------------------------------------------------------------------------------------------------------------ 2 SN2020WNT WFC3/IR MULTIAC IRSUB512 F140W NSAMP=4, SAMP-SEQ=SPARS25 1 DEF CUM (139.234 S) ------------------------------------------------------------------------------------------------------------------------------------ 3 SN2020WNT WFC3/IR MULTIAC IRSUB512 F105W NSAMP=4, SAMP-SEQ=SPARS25 1 DEF CUM (139.234 S) ------------------------------------------------------------------------------------------------------------------------------------ 4 SN2020WNT WFC3/UVI ACCUM UVIS2-C1K F475W FLASH=4 1 400 S PATTERN 2 4-5 S 1C-CTE see below (770 S) ------------------------------------------------------------------------------------------------------------------------------------ 5 SN2020WNT WFC3/UVI ACCUM UVIS2-C1K F275W FLASH=11 1 400 S S 1C-CTE see below (770 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 | ------------------------------------------------------------------------------------------------------------------------------------ SN2020WNT 1 WFC3/IR MULTIAC IRSUB512 F160W 1 none none none 1 N/A CUM SN2020WNT 1 WFC3/IR MULTIAC IRSUB512 F160W 2 none none none 1 N/A CUM SN2020WNT 2 WFC3/IR MULTIAC IRSUB512 F140W 1 none none none 1 N/A CUM SN2020WNT 2 WFC3/IR MULTIAC IRSUB512 F140W 2 none none none 1 N/A CUM SN2020WNT 3 WFC3/IR MULTIAC IRSUB512 F105W 1 none none none 1 N/A CUM SN2020WNT 3 WFC3/IR MULTIAC IRSUB512 F105W 2 none none none 1 N/A CUM SN2020WNT 4 WFC3/UVI ACCUM UVIS2-C1 F475W 1 none none none 1 385.0 S S K1C-CTE SN2020WNT 4 WFC3/UVI ACCUM UVIS2-C1 F475W 2 none none none 1 385.0 S S K1C-CTE 16768( 7) - 10-Jan-2022 20:12:03 - [ 5] 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 | ------------------------------------------------------------------------------------------------------------------------------------ SN2020WNT 5 WFC3/UVI ACCUM UVIS2-C1 F275W 1 none none none 1 385.0 S S K1C-CTE SN2020WNT 5 WFC3/UVI ACCUM UVIS2-C1 F275W 2 none none none 1 385.0 S S K1C-CTE 16768( 7) - 10-Jan-2022 20:12:03 - [ 6] Visit: 02 Visit Requirements: ORIENT 298D TO 310 D; ORIENT 112D TO 130 D; ORIENT 185D TO 205 D; ORIENT 5D TO 25 D; AFTER 01 BY 20 D TO 100 D 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 SN2020WNT WFC3/IR MULTIAC GRISM1024 F140W SAMP-SEQ=SPARS10, NSAMP=5 1 DEF PATTERN 1 1-4 CUM (85.872 S) ------------------------------------------------------------------------------------------------------------------------------------ 2 SN2020WNT WFC3/IR MULTIAC GRISM1024 G141 SAMP-SEQ=SPARS50, NSAMP=13 1 DEF CUM (1205.875 S) ------------------------------------------------------------------------------------------------------------------------------------ 3 SN2020WNT WFC3/IR MULTIAC GRISM1024 F105W SAMP-SEQ=SPARS10, NSAMP=4 1 DEF (65.87 CUM S) ------------------------------------------------------------------------------------------------------------------------------------ 4 SN2020WNT WFC3/IR MULTIAC GRISM1024 G102 SAMP-SEQ=SPARS50, NSAMP=13 1 DEF CUM (1205.875 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 | ------------------------------------------------------------------------------------------------------------------------------------ SN2020WNT 1 WFC3/IR MULTIAC GRISM102 F140W 1 none none none 1 N/A CUM 4 SN2020WNT 1 WFC3/IR MULTIAC GRISM102 F140W 2 none none none 1 N/A CUM 4 SN2020WNT 2 WFC3/IR MULTIAC GRISM102 G141 1 none none none 1 N/A CUM 4 SN2020WNT 2 WFC3/IR MULTIAC GRISM102 G141 2 none none none 1 N/A CUM 4 SN2020WNT 3 WFC3/IR MULTIAC GRISM102 F105W 1 none none none 1 N/A CUM 4 SN2020WNT 3 WFC3/IR MULTIAC GRISM102 F105W 2 none none none 1 N/A CUM 4 SN2020WNT 4 WFC3/IR MULTIAC GRISM102 G102 1 none none none 1 N/A CUM 4 SN2020WNT 4 WFC3/IR MULTIAC GRISM102 G102 2 none none none 1 N/A CUM 4 16768( 7) - 10-Jan-2022 20:12:03 - [ 7] Summary Form for Proposal 16768 Item Used in this proposal ------------------------------------------------------------------------------------------------------------------------------------ Apertures GRISM1024, IRSUB512, UVIS2-C1K1C-CTE ------------------------------------------------------------------------------------------------------------------------------------ Configurations WFC3/IR, WFC3/UVIS ------------------------------------------------------------------------------------------------------------------------------------ Opmodes ACCUM, MULTIACCUM ------------------------------------------------------------------------------------------------------------------------------------ Optional Parameters FLASH=11, FLASH=4, NSAMP=13, NSAMP=4, NSAMP=5, NSAMP=6, SAMP-SEQ=SPARS10, SAMP-SEQ=SPARS25, SAMP-SEQ=SPARS50 ------------------------------------------------------------------------------------------------------------------------------------ Special Requirements AFTER 01 BY 20 D TO 100 D, ORIENT 112D TO 130 D, ORIENT 185D TO 205 D, ORIENT 298D TO 310 D, ORIENT 5D TO 25 D, PATTERN 1 1-3, PATTERN 1 1-4, PATTERN 2 4-5 ------------------------------------------------------------------------------------------------------------------------------------ Spectral Elements F105W, F140W, F160W, F275W, F475W, G102, G141 ------------------------------------------------------------------------------------------------------------------------------------ Target Names SN2020WNT ------------------------------------------------------------------------------------------------------------------------------------