15600( 4) - 23-Jul-2018 14:07:37 - [ 1] HUBBLE SPACE TELESCOPE OBSERVING PROGRAM 15600 Version: 4 Check-in Time: 23-Jul-2018 14:07:37 STScI Edit Number: 0 Title Seeing The Cow in Ultraviolet Light ------------------------------------------------------------------------------------ Type Cycle GO/DD 25 ------------------------------------------------------------------------------------ Investigators Contact? PI: Prof. Ryan Foley University of California - Santa Cruz Y CoI: Maria Drout Carnegie Institution of Washington N CoI: Dr. Anthony Piro Carnegie Institution of Washington N CoI: Dr. Charles Kilpatrick University of California - Santa Cruz N CoI: Mr. Mark Magee The Queen's University of Belfast N CoI: Dr. Kate Maguire The Queen's University of Belfast N CoI: Dr. Simon Prentice The Queen's University of Belfast N CoI: Dr. Armin Rest Space Telescope Science Institute N CoI: Mr. Cesar Rojas-Bravo University of California - Santa Cruz N CoI: Dr. Stephen J. Smartt The Queen's University of Belfast N ------------------------------------------------------------------------------------ Abstract With an exponentially increasing number of explosive transient discoveries, we are finding increasingly diverse and spectacular ways for stars to die. In the last few years, we identified a class of rapidly evolving transients - objects with luminosities similar to supernovae (SN), but fade ten times faster. They are distinct from normal SN, and represent a new variety of stellar explosion. We recently discovered a truly unique member, AT 2018cow ("The Cow"). It is similar to other rapidly-evolving transients, but represents both the most luminous and fastest event discovered to date. In addition, it exhibits a significant non-thermal component, manifesting as both strong radio emission and particularly luminous, long-lasting, and variable X-ray emission. Such a transient was not predicted and no physical model to-date explains all observations. The prompt discovery, high luminosity, and close distance (60 Mpc) of The Cow offer an unique opportunity to probe the nature of these explosions. Currently, the best models are either a magnetar-powered explosion or a fallback supernova. While current observations cannot distinguish between these models, continued photometric monitoring in the UV with HST can. Multiple imaging epochs can also provide a link between the thermal and non-thermal components if the X-ray decline changes significantly during this campaign. A UV spectrum will reveal unique spectral species, constraining the nature of the progenitor star. Here we request HST UV spectra and photometry to determine the progenitor and explosion scenario for this extraordinary event and to provide a legacy data set for future "bovine" transients. ------------------------------------------------------------------------------------ Observations Description ------------------------ We plan to image AT 2018cow in 4 UV filters over 3 epochs. ------------------------------------------------------------------------------------ 15600( 4) - 23-Jul-2018 14:07:37 - [ 2] TARGET LIST Fixed Targets ------------------------------------------------------------------------------------------------------------------------------------ Tar| Target | Target | Target |Coord | Radial | Flux data No | Name | Description | Position |Eqnx | Vel. | ------------------------------------------------------------------------------------------------------------------------------------ 1 AT2018COW STAR, SUPERNOVA, X-RAY RA=16H16M0.2200S +/- 0.1", J2000 V = 18.0 +/- 0.1 UVW1 = 15.98 and WUVW2 TRANSIENT DEC=+22D16'4.83" +/- 0.1" = 16.13 on 7/7 Reference Frame: ICRS ------------------------------------------------------------------------------------------------------------------------------------ 15600( 4) - 23-Jul-2018 14:07:37 - [ 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 ------------------------------------------------------------------------------------------------------------------------------------ 15600( 4) - 23-Jul-2018 14:07:37 - [ 4] Visit: 01 Visit Requirements: BEFORE 09-AUG-2018:00:00:00 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 AT2018COW WFC3/UVI ACCUM UVIS2-C1K F336W FLASH=12 1 75 S (150 PATTERN 1 1-4 S 1C-SUB S) ------------------------------------------------------------------------------------------------------------------------------------ 2 AT2018COW WFC3/UVI ACCUM UVIS2-C1K F275W FLASH=12 1 140 S (280 S 1C-SUB S) ------------------------------------------------------------------------------------------------------------------------------------ 3 AT2018COW WFC3/UVI ACCUM UVIS2-C1K F225W FLASH=12 1 385 S (770 S 1C-SUB S) ------------------------------------------------------------------------------------------------------------------------------------ 4 AT2018COW WFC3/UVI ACCUM UVIS2-C1K F218W FLASH=12 1 440 S (880 S 1C-SUB 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 | ------------------------------------------------------------------------------------------------------------------------------------ AT2018COW 1 WFC3/UVI ACCUM UVIS2-C1 F336W 1 none none none 1 N/A S K1C-SUB AT2018COW 1 WFC3/UVI ACCUM UVIS2-C1 F336W 2 none none none 1 N/A S K1C-SUB AT2018COW 2 WFC3/UVI ACCUM UVIS2-C1 F275W 1 none none none 1 N/A S K1C-SUB AT2018COW 2 WFC3/UVI ACCUM UVIS2-C1 F275W 2 none none none 1 N/A S K1C-SUB AT2018COW 3 WFC3/UVI ACCUM UVIS2-C1 F225W 1 none none none 1 N/A S K1C-SUB AT2018COW 3 WFC3/UVI ACCUM UVIS2-C1 F225W 2 none none none 1 N/A S K1C-SUB AT2018COW 4 WFC3/UVI ACCUM UVIS2-C1 F218W 1 none none none 1 N/A S K1C-SUB AT2018COW 4 WFC3/UVI ACCUM UVIS2-C1 F218W 2 none none none 1 N/A S K1C-SUB 15600( 4) - 23-Jul-2018 14:07:37 - [ 5] Visit: 02 Visit Requirements: SAME ORIENT AS 01; AFTER 01 BY 4 D TO 6 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 AT2018COW WFC3/UVI ACCUM UVIS2-C1K F336W FLASH=12 1 75 S (150 POS TARG -0.5, -0.5; S 1C-SUB S) PATTERN 1 1-4 ------------------------------------------------------------------------------------------------------------------------------------ 2 AT2018COW WFC3/UVI ACCUM UVIS2-C1K F275W FLASH=12 1 140 S (280 POS TARG -0.5, -0.5 S 1C-SUB S) ------------------------------------------------------------------------------------------------------------------------------------ 3 AT2018COW WFC3/UVI ACCUM UVIS2-C1K F225W FLASH=12 1 385 S (770 POS TARG -0.5, -0.5 S 1C-SUB S) ------------------------------------------------------------------------------------------------------------------------------------ 4 AT2018COW WFC3/UVI ACCUM UVIS2-C1K F218W FLASH=12 1 440 S (880 POS TARG -0.5, -0.5 S 1C-SUB 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 | ------------------------------------------------------------------------------------------------------------------------------------ AT2018COW 1 WFC3/UVI ACCUM UVIS2-C1 F336W 1 none none none 1 N/A S K1C-SUB AT2018COW 1 WFC3/UVI ACCUM UVIS2-C1 F336W 2 none none none 1 N/A S K1C-SUB AT2018COW 2 WFC3/UVI ACCUM UVIS2-C1 F275W 1 none none none 1 N/A S K1C-SUB AT2018COW 2 WFC3/UVI ACCUM UVIS2-C1 F275W 2 none none none 1 N/A S K1C-SUB AT2018COW 3 WFC3/UVI ACCUM UVIS2-C1 F225W 1 none none none 1 N/A S K1C-SUB AT2018COW 3 WFC3/UVI ACCUM UVIS2-C1 F225W 2 none none none 1 N/A S K1C-SUB AT2018COW 4 WFC3/UVI ACCUM UVIS2-C1 F218W 1 none none none 1 N/A S K1C-SUB AT2018COW 4 WFC3/UVI ACCUM UVIS2-C1 F218W 2 none none none 1 N/A S K1C-SUB 15600( 4) - 23-Jul-2018 14:07:37 - [ 6] Visit: 03 Visit Requirements: SAME ORIENT AS 01; AFTER 02 BY 4 D TO 6 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 AT2018COW WFC3/UVI ACCUM UVIS2-C1K F336W FLASH=12 1 75 S (150 POS TARG -1, -1; PATTERN S 1C-SUB S) 1 1-4 ------------------------------------------------------------------------------------------------------------------------------------ 2 AT2018COW WFC3/UVI ACCUM UVIS2-C1K F275W FLASH=12 1 140 S (280 POS TARG -1, -1 S 1C-SUB S) ------------------------------------------------------------------------------------------------------------------------------------ 3 AT2018COW WFC3/UVI ACCUM UVIS2-C1K F225W FLASH=12 1 385 S (770 POS TARG -1, -1 S 1C-SUB S) ------------------------------------------------------------------------------------------------------------------------------------ 4 AT2018COW WFC3/UVI ACCUM UVIS2-C1K F218W FLASH=12 1 440 S (880 POS TARG -1, -1 S 1C-SUB 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 | ------------------------------------------------------------------------------------------------------------------------------------ AT2018COW 1 WFC3/UVI ACCUM UVIS2-C1 F336W 1 none none none 1 N/A S K1C-SUB AT2018COW 1 WFC3/UVI ACCUM UVIS2-C1 F336W 2 none none none 1 N/A S K1C-SUB AT2018COW 2 WFC3/UVI ACCUM UVIS2-C1 F275W 1 none none none 1 N/A S K1C-SUB AT2018COW 2 WFC3/UVI ACCUM UVIS2-C1 F275W 2 none none none 1 N/A S K1C-SUB AT2018COW 3 WFC3/UVI ACCUM UVIS2-C1 F225W 1 none none none 1 N/A S K1C-SUB AT2018COW 3 WFC3/UVI ACCUM UVIS2-C1 F225W 2 none none none 1 N/A S K1C-SUB AT2018COW 4 WFC3/UVI ACCUM UVIS2-C1 F218W 1 none none none 1 N/A S K1C-SUB AT2018COW 4 WFC3/UVI ACCUM UVIS2-C1 F218W 2 none none none 1 N/A S K1C-SUB 15600( 4) - 23-Jul-2018 14:07:37 - [ 7] Summary Form for Proposal 15600 Item Used in this proposal ------------------------------------------------------------------------------------------------------------------------------------ Apertures UVIS2-C1K1C-SUB ------------------------------------------------------------------------------------------------------------------------------------ Configurations WFC3/UVIS ------------------------------------------------------------------------------------------------------------------------------------ Opmodes ACCUM ------------------------------------------------------------------------------------------------------------------------------------ Optional Parameters FLASH=12 ------------------------------------------------------------------------------------------------------------------------------------ Special Requirements AFTER 01 BY 4 D TO 6 D, AFTER 02 BY 4 D TO 6 D, BEFORE 09-AUG-2018:00:00:00, PATTERN 1 1-4, POS TARG -0.5, -0.5, POS TARG -1, -1, SAME ORIENT AS 01 ------------------------------------------------------------------------------------------------------------------------------------ Spectral Elements F218W, F225W, F275W, F336W ------------------------------------------------------------------------------------------------------------------------------------ Target Names AT2018COW ------------------------------------------------------------------------------------------------------------------------------------