14346( 5) - 18-Dec-2015 18:32:00 - [ 1] HUBBLE SPACE TELESCOPE OBSERVING PROGRAM 14346 Version: 5 Check-in Time: 18-Dec-2015 18:32:00 STScI Edit Number: 0 Title Constraining the Position of the Most Luminous Supernova Ever Foundb ------------------------------------------------------------------------------------ Type Cycle GO/DD 23 ------------------------------------------------------------------------------------ Investigators Contact? PI: Dr. C. S. Kochanek The Ohio State University Y CoI: Dr. Krzysztof Z. Stanek The Ohio State University N CoI: Dr. Benjamin John Shappee Carnegie Institution of Washington N ------------------------------------------------------------------------------------ Abstract In ASASSN-15lh we appear to have found the most superluminous supernova discovered to date, with a peak luminosity in excess of 10^45 ergs/s. It is an SLSN-I with no hydrogen or helium emission -- its only spectral feature is an absorption trough attributed to OII. While its properties match other SLSN-I and do not match any known AGN, including known tidal disruption events, its position is very close to the core of its host galaxy. We propose HST observations to measure or constrain the offset down to scales under 10~pc. DD time is required because the transient will not be present by the time any Cycle 24 observations are scheduled. ------------------------------------------------------------------------------------ Observations Description ------------------------ We will obtain two WFC3/UVIS F606W images of the target. One while the transient is present but neither too bright nor too faint, one one when the transient is gone. The estimated time frames are October/November 2015 for the first and February 2016 or later for the second. Each visit will be done using six position sub-pixel dithers to control for cosmic rays/hot pixels and produce a clean, sub-sampled PSF. ****READ CAREFULLY FOR EPOCH1 **** We have updated the slope of the light curve, and also note that it closely matches the decay rate of another SLSN-I, iPTF13ajg, which seems to have maintained this slope out to the time scales needed for these observations. Following a discussion with Alison Vick, the exposure times for epoch 1 were reduced by 15-20% over the maximum possible, which opened up the scheduling window to cover Sept 1 to November 30 rather than the orginal windows of Sept 7-26 and Oct 31-Nov 19. The reduction in the S/N of the observations should have no significant impact on the results 14346( 5) - 18-Dec-2015 18:32:00 - [ 2] The **ESTIMATED** magnitude of the transient is Sept 1 19.1 Oct 1 19.9 Nov 1 20.8 Dec 1 21.6 so I have set the timing constraint to be the month of October -- in September it is too bright and as we reduce the exposure times there will be fewer background sources (to ensure good registration to epoch #2) and in November it is getting too faint (and the reliability of these estimates is increasingly dubious). Should more scheduling flexibility be needed, please contact me and we can try to adjust the strategy. ***END READ CAREFULLY FOR EPOCH2 **** The extrapolated magnitude is predicted to be faint enough for the 2nd observation in February 2016 or later, as included in the proposal. However, if you want to schedule it early in this period, we should use the results of the first epoch (and other monitoring data) to verify that the extrapolation remains valid. Since there was no reason not to simply use windows that maximize the total integration time, "auto-adjust" was used to optimize the exposure times. ***now back to just description of process***** Difference imaging methods will then be used to remove the host from the epoch with the transient and ensure proper alignment of the two epochs, and then we will measure the relative positions of the transient and the galaxy core to determine the offset. ------------------------------------------------------------------------------------ 14346( 5) - 18-Dec-2015 18:32:00 - [ 3] TARGET LIST Fixed Targets ------------------------------------------------------------------------------------------------------------------------------------ Tar| Target | Target | Target |Coord | Radial | Flux data No | Name | Description | Position |Eqnx | Vel. | ------------------------------------------------------------------------------------------------------------------------------------ 1 ASASSN-15LH EXT-STAR, ACCRETION RA=22H02M15.4500S, J2000 V = 20 DISK, BULGE, SUPERNOVA DEC=-61D39'34.64" Reference Frame: Other: astrometry.net solutions ------------------------------------------------------------------------------------------------------------------------------------ 14346( 5) - 18-Dec-2015 18:32:00 - [ 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 ------------------------------------------------------------------------------------------------------------------------------------ Pattern_Number: 2 Primary_Pattern Secondary_Pattern Pattern_Type WFC3-UVIS-DITHER-LINE Pattern_Purpose DITHER Number_Of_Points 3 Point_Spacing 0.145 Line_Spacing Coordinate_Frame POS-TARG Pattern_Orient 46.84 Angle_Between_Sides Center_Pattern NO ------------------------------------------------------------------------------------------------------------------------------------ Pattern_Number: 3 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 ------------------------------------------------------------------------------------------------------------------------------------ 14346( 5) - 18-Dec-2015 18:32:00 - [ 5] Visit: 02 Visit Requirements: AFTER 01-JUL-2016:00:00:00 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 ASASSN-15LH WFC3/UVI ACCUM UVIS2 F606W 1 350 S PATTERN 1 1 S see below (1664 S) ------------------------------------------------------------------------------------------------------------------------------------ 2 ASASSN-15LH WFC3/UVI ACCUM UVIS2 F606W 1 350 S PATTERN 3 2 S see below (832 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 | ------------------------------------------------------------------------------------------------------------------------------------ ASASSN-15LH 1 WFC3/UVI ACCUM UVIS2 F606W 1 none none none 1 416.0 S S ASASSN-15LH 1 WFC3/UVI ACCUM UVIS2 F606W 2 none none none 1 416.0 S S ASASSN-15LH 1 WFC3/UVI ACCUM UVIS2 F606W 3 none none none 1 416.0 S S ASASSN-15LH 1 WFC3/UVI ACCUM UVIS2 F606W 4 none none none 1 416.0 S S ASASSN-15LH 2 WFC3/UVI ACCUM UVIS2 F606W 1 none none none 1 416.0 S S ASASSN-15LH 2 WFC3/UVI ACCUM UVIS2 F606W 2 none none none 1 416.0 S S 14346( 5) - 18-Dec-2015 18:32:00 - [ 6] Visit: 04 Visit Requirements: BETWEEN 01-OCT-2015:00:00:00 AND 01-MAR-2016:00:00:00 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 ASASSN-15LH WFC3/UVI ACCUM UVIS2-M1K F606W FLASH=10, CR-SPLIT=5 1 300 S PATTERN 1 1 S 1C-SUB see below (1240 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 | ------------------------------------------------------------------------------------------------------------------------------------ ASASSN-15LH 1 WFC3/UVI ACCUM UVIS2-M1 F606W 1 none none 1 1 62.0 S S K1C-SUB ASASSN-15LH 1 WFC3/UVI ACCUM UVIS2-M1 F606W 1 none none 2 1 62.0 S S K1C-SUB ASASSN-15LH 1 WFC3/UVI ACCUM UVIS2-M1 F606W 1 none none 3 1 62.0 S S K1C-SUB ASASSN-15LH 1 WFC3/UVI ACCUM UVIS2-M1 F606W 1 none none 4 1 62.0 S S K1C-SUB ASASSN-15LH 1 WFC3/UVI ACCUM UVIS2-M1 F606W 1 none none 5 1 62.0 S S K1C-SUB ASASSN-15LH 1 WFC3/UVI ACCUM UVIS2-M1 F606W 2 none none 1 1 62.0 S S K1C-SUB ASASSN-15LH 1 WFC3/UVI ACCUM UVIS2-M1 F606W 2 none none 2 1 62.0 S S K1C-SUB ASASSN-15LH 1 WFC3/UVI ACCUM UVIS2-M1 F606W 2 none none 3 1 62.0 S S K1C-SUB ASASSN-15LH 1 WFC3/UVI ACCUM UVIS2-M1 F606W 2 none none 4 1 62.0 S S K1C-SUB ASASSN-15LH 1 WFC3/UVI ACCUM UVIS2-M1 F606W 2 none none 5 1 62.0 S S K1C-SUB ASASSN-15LH 1 WFC3/UVI ACCUM UVIS2-M1 F606W 3 none none 1 1 62.0 S S K1C-SUB ASASSN-15LH 1 WFC3/UVI ACCUM UVIS2-M1 F606W 3 none none 2 1 62.0 S S K1C-SUB ASASSN-15LH 1 WFC3/UVI ACCUM UVIS2-M1 F606W 3 none none 3 1 62.0 S S K1C-SUB ASASSN-15LH 1 WFC3/UVI ACCUM UVIS2-M1 F606W 3 none none 4 1 62.0 S S K1C-SUB ASASSN-15LH 1 WFC3/UVI ACCUM UVIS2-M1 F606W 3 none none 5 1 62.0 S S K1C-SUB ASASSN-15LH 1 WFC3/UVI ACCUM UVIS2-M1 F606W 4 none none 1 1 62.0 S S K1C-SUB 14346( 5) - 18-Dec-2015 18:32:00 - [ 7] 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 | ------------------------------------------------------------------------------------------------------------------------------------ ASASSN-15LH 1 WFC3/UVI ACCUM UVIS2-M1 F606W 4 none none 2 1 62.0 S S K1C-SUB ASASSN-15LH 1 WFC3/UVI ACCUM UVIS2-M1 F606W 4 none none 3 1 62.0 S S K1C-SUB ASASSN-15LH 1 WFC3/UVI ACCUM UVIS2-M1 F606W 4 none none 4 1 62.0 S S K1C-SUB ASASSN-15LH 1 WFC3/UVI ACCUM UVIS2-M1 F606W 4 none none 5 1 62.0 S S K1C-SUB 14346( 5) - 18-Dec-2015 18:32:00 - [ 8] Summary Form for Proposal 14346 Item Used in this proposal ------------------------------------------------------------------------------------------------------------------------------------ Apertures UVIS2, UVIS2-M1K1C-SUB ------------------------------------------------------------------------------------------------------------------------------------ Configurations WFC3/UVIS ------------------------------------------------------------------------------------------------------------------------------------ Opmodes ACCUM ------------------------------------------------------------------------------------------------------------------------------------ Optional Parameters CR-SPLIT=5, FLASH=10 ------------------------------------------------------------------------------------------------------------------------------------ Special Requirements AFTER 01-JUL-2016:00:00:00, BETWEEN 01-OCT-2015:00:00:00 AND 01-MAR-2016:00:00:00, PATTERN 1 1, PATTERN 3 2 ------------------------------------------------------------------------------------------------------------------------------------ Spectral Elements F606W ------------------------------------------------------------------------------------------------------------------------------------ Target Names ASASSN-15LH ------------------------------------------------------------------------------------------------------------------------------------