13869( 2) - 21-Jul-2014 17:18:54 - [ 1] HUBBLE SPACE TELESCOPE OBSERVING PROGRAM 13869 Version: 2 Check-in Time: 21-Jul-2014 17:18:54 STScI Edit Number: 0 Title Pinpointing the location and host of the candidate tidal disruption Swift J1112.3-8238 ------------------------------------------------------------------------------------ Type Cycle GO 22 ------------------------------------------------------------------------------------ Investigators Contact? PI: Prof. Andrew J. Levan The University of Warwick Y CoI: Mr. Gregory Brown The University of Warwick N CoI: Prof. Nial R. Tanvir University of Leicester N CoI: Dr. Elizabeth R. Stanway The University of Warwick N CoI: Dr. Andrew S. Fruchter Space Telescope Science Institute N CoI: Dr. Stephen Bradley Cenko NASA Goddard Space Flight Center N ------------------------------------------------------------------------------------ Abstract Multiwavelength observations over the past few years have revealed a new class of high energy transient. These systems persist as bright gamma-ray sources for days, with luminosities in excess of the Eddington limit for a 10^10 solar mass black hole. They are accompanied by bright, long-lived (months to years) X-ray emission, and rather fainter, but still clearly detectable optical and IR counterparts. They are suggested to arise from the tidal disruption of stars in the nuclei of their host galaxies, which create a powerful relativistic outflow. In the first case (Swift J1644+57) astrometry ties the transient to nucleus of its host galaxy, while in a second (Swift J2058.4+0516) the host is exceptionally faint making (H~26.5) such tests challenging . However, other models have been postulated, such as the collapse of a giant star, where the outer envelope forms a disc that powers the observed transients, akin to a scaled-up gamma-ray burst. A key distinguishing feature between the two progenitors is their expected locations. Tidal disruptions are nuclear, while GRB-like events are consistent with the nuclei of their hosts only 1/6 of the time. Here we propose observations of an event recently uncovered in an archival search. These will resolve its host galaxy and provide a precise location on the host. An IR visit will also provide a colors, and an estimate of the stellar and (through the bulge mass -- black hole mass relation) black hole mass. These data will provide the key astrometric and photometric evidence to disentagle competing models for these events, and will greatly aid the development of a definitive understanding of this new class of transient. ------------------------------------------------------------------------------------ Observations Description ------------------------ Our proposal is to obtain observations of the candidate relativistic tidal disruption event Swift J1112-8238. To do this we will obtain a single orbit of observations using WFC3 (IR and UVIS). For both observations we specify a somewhat restricted range of roll angles in order to avoid diffraction spikes from the relatively proximate (6"), bright (R~16.5, H~13) star. The Galactic lattitude of the source is moderate so there are additional bright sources in the field. However, inspection of archival imaging suggests that diffraction spikes from these should not reach the source 13869( 2) - 21-Jul-2014 17:18:54 - [ 2] position. For the IR observations we will obtain a standard 4 point dither pattern, and the STEP non-destructive read sequences for maximum dynamic range (to allow for astrometry with the bright stars in non-saturated images). FOr the UVIS observations we will also obtain the standard 4-point dither pattern, and will utilize UVIS2. We have include a POSTARG offset that places the source towards the corner of the chip in order to minimize the impact of CTE. ------------------------------------------------------------------------------------ 13869( 2) - 21-Jul-2014 17:18:54 - [ 3] TARGET LIST Fixed Targets ------------------------------------------------------------------------------------------------------------------------------------ Tar| Target | Target | Target |Coord | Radial | Flux data No | Name | Description | Position |Eqnx | Vel. | ------------------------------------------------------------------------------------------------------------------------------------ 1 SWIFT-J1112. GALAXY, ACCRETION DISK, RA=11H11M47.7230S, J2000 i '= 23.2+/-0.1 , r' = 23.8+/-0.1, z' 2-8238 HIGH REDSHIFT GALAXY DEC=-82D38'45.01" = 23.0 +/- 0.1 Reference Frame: Other: SIMBAD Comments: This object was generated by the targetselector and retrieved from the SIMBAD database. ------------------------------------------------------------------------------------------------------------------------------------ 13869( 2) - 21-Jul-2014 17:18:54 - [ 4] Patterns ------------------------------------------------------------------------------------------------------------------------------------ Pattern_Number: 1 Primary_Pattern Secondary_Pattern Pattern_Type WFC3-IR-DITHER-BOX-MIN Pattern_Purpose DITHER Number_Of_Points 4 Point_Spacing 0.572 Line_Spacing 0.365 Coordinate_Frame POS-TARG Pattern_Orient 18.528 Angle_Between_Sides 74.653 Center_Pattern NO ------------------------------------------------------------------------------------------------------------------------------------ Pattern_Number: 2 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 ------------------------------------------------------------------------------------------------------------------------------------ 13869( 2) - 21-Jul-2014 17:18:54 - [ 5] Visit: 01 Visit Requirements: ORIENT 15D TO 65 D; ORIENT 105D TO 155 D; ORIENT 195D TO 245 D; ORIENT 285D TO 335 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 SWIFT-J1112 WFC3/IR MULTIAC IR F160W SAMP-SEQ=STEP50, NSAMP=10 1 DEF PATTERN 1 1 .2-8238 CUM (996.928 S) ------------------------------------------------------------------------------------------------------------------------------------ 2 SWIFT-J1112 WFC3/UVI ACCUM UVIS2 F606W 1 360 S POS TARG -60, -30; .2-8238 S see below PATTERN 2 2 (1568 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 | ------------------------------------------------------------------------------------------------------------------------------------ SWIFT-J1112.2-8238 1 WFC3/IR MULTIAC IR F160W 1 none none none 1 N/A CUM SWIFT-J1112.2-8238 1 WFC3/IR MULTIAC IR F160W 2 none none none 1 N/A CUM SWIFT-J1112.2-8238 1 WFC3/IR MULTIAC IR F160W 3 none none none 1 N/A CUM SWIFT-J1112.2-8238 1 WFC3/IR MULTIAC IR F160W 4 none none none 1 N/A CUM SWIFT-J1112.2-8238 2 WFC3/UVI ACCUM UVIS2 F606W 1 none none none 1 392.0 S S SWIFT-J1112.2-8238 2 WFC3/UVI ACCUM UVIS2 F606W 2 none none none 1 392.0 S S SWIFT-J1112.2-8238 2 WFC3/UVI ACCUM UVIS2 F606W 3 none none none 1 392.0 S S SWIFT-J1112.2-8238 2 WFC3/UVI ACCUM UVIS2 F606W 4 none none none 1 392.0 S S 13869( 2) - 21-Jul-2014 17:18:54 - [ 6] Summary Form for Proposal 13869 Item Used in this proposal ------------------------------------------------------------------------------------------------------------------------------------ Apertures IR, UVIS2 ------------------------------------------------------------------------------------------------------------------------------------ Configurations WFC3/IR, WFC3/UVIS ------------------------------------------------------------------------------------------------------------------------------------ Opmodes ACCUM, MULTIACCUM ------------------------------------------------------------------------------------------------------------------------------------ Optional Parameters NSAMP=10, SAMP-SEQ=STEP50 ------------------------------------------------------------------------------------------------------------------------------------ Special Requirements ORIENT 105D TO 155 D, ORIENT 15D TO 65 D, ORIENT 195D TO 245 D, ORIENT 285D TO 335 D, PATTERN 1 1, PATTERN 2 2, POS TARG -60, -30 ------------------------------------------------------------------------------------------------------------------------------------ Spectral Elements F160W, F606W ------------------------------------------------------------------------------------------------------------------------------------ Target Names SWIFT-J1112.2-8238 ------------------------------------------------------------------------------------------------------------------------------------