14043( 2) - 02-Jan-2015 15:46:05 - [ 1] HUBBLE SPACE TELESCOPE OBSERVING PROGRAM 14043 Version: 2 Check-in Time: 02-Jan-2015 15:46:05 STScI Edit Number: 0 Title HST Follow-up of a Fast Unexplained X-ray Transient in the CDF-S ------------------------------------------------------------------------------------ Type Cycle GO/DD 22 ------------------------------------------------------------------------------------ Investigators Contact? PI: Dr. Franz Bauer Space Science Institute Y CoI: Dr. Ezequiel Treister Universidad de Concepcion N CoI: Dr. Steve Schulze Pontificia Universidad Catolica de Chile N CoI: Francisco Forster Universidad de Chile, CMM N CoI: Dr. Giuliano Pignata Universidad Andres Bello N CoI: Prof. Kevin Schawinski Eidgenossiche Technische Hochschule (ETH) N CoI: Dr. W. Nielsen Brandt The Pennsylvania State University N CoI: Dr. Bin Luo The Pennsylvania State University N CoI: Prof. Ken'ichi Nomoto Institute for Physics and Mathematics of N the Universe CoI: Prof. Keiichi Maeda Kyoto University N CoI: Alexey Tolstov University of Tokyo N CoI: Prof. Nozomu Tominaga Konan University N ------------------------------------------------------------------------------------ Abstract A fast X-ray transient was discovered by Chandra in the Chandra Deep Field-South field on 2014 October 01. The transient lasted only a few ks in duration, reaching a 0.5-8 keV luminosity of ~1e45 erg/s (assuming z=0.3 from nearest galaxy), with no detection in ~4.5 Ms of previous data nor in a subseqent ~1.2 Ms of exposure. No optical transient down to R_AB~26.5 (2 sigma limit) has been found yet in three epochs (~0.05, 17, and 28 days after discovery). At this point, the observations appear inconsistent with all known Galactic phenomena, tidal disruption events, low-z gamma-ray bursts (GRB), and most types of supernovae (SNe). The transient could still be: 1) a SN from a SN1987A-like blue supergiant (BSG) progenitor, which are known to produce very late rising SNe; 2) a SN with little or no 56Ni due to fallback; 3) a highly extinguished or high-z GRB; or 4) a new type of transient. We request 1 orbit with HST to firmly confirm/rule out all known SNe light curves. If no counterpart is found, a high-z GRB or a new class of X-ray transient are all that remain. Importantly, the detection in the small CDF-S field may imply up to a factor of 100 higher rate than Swift/BAT. ------------------------------------------------------------------------------------ Observations Description ------------------------ TBD ------------------------------------------------------------------------------------ 14043( 2) - 02-Jan-2015 15:46:05 - [ 2] TARGET LIST Fixed Targets ------------------------------------------------------------------------------------------------------------------------------------ Tar| Target | Target | Target |Coord | Radial | Flux data No | Name | Description | Position |Eqnx | Vel. | ------------------------------------------------------------------------------------------------------------------------------------ 1 CDFS-XT1 UNIDENTIFIED, X-RAY RA=03H32M38.7980S +/- 0.4", J2000 V = 28.4 +/- 2.0 EMITTER DEC=-27D51'34.08" +/- 0.4" Reference Frame: ICRS Comments: CDFS-XT1 is an X-ray transient with no optical counterpart detected as yet. Two potential host galaxies lie within the error Chandra error circle, with R=27.3 and 27.5 respectively. As stated in the proposal, we wish to obtain a F110W image to enable image subtraction against previous F110W images of the field to probe as for a transient signature down to the level indicated. Epoch of Position RA proper motion (seconds of time/yr) DEC Proper Motion (arcsec/yr) Annual Parallax (arcsec) 2000 0.0 0.0 0.0 ------------------------------------------------------------------------------------------------------------------------------------ 14043( 2) - 02-Jan-2015 15:46:05 - [ 3] 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 ------------------------------------------------------------------------------------------------------------------------------------ 14043( 2) - 02-Jan-2015 15:46:05 - [ 4] Visit: 01 Visit Requirements: BETWEEN 31-DEC-2014:00:00:00 AND 31-JAN-2015:00:00:00 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 CDFS-XT1 WFC3/IR MULTIAC IR-FIX F110W NSAMP=14, SAMP-SEQ=SPARS50 1 DEF PATTERN 1 1 CUM (2611.753 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 | ------------------------------------------------------------------------------------------------------------------------------------ CDFS-XT1 1 WFC3/IR MULTIAC IR-FIX F110W 1 none none none 1 N/A CUM CDFS-XT1 1 WFC3/IR MULTIAC IR-FIX F110W 2 none none none 1 N/A CUM CDFS-XT1 1 WFC3/IR MULTIAC IR-FIX F110W 3 none none none 1 N/A CUM CDFS-XT1 1 WFC3/IR MULTIAC IR-FIX F110W 4 none none none 1 N/A CUM 14043( 2) - 02-Jan-2015 15:46:05 - [ 5] Summary Form for Proposal 14043 Item Used in this proposal ------------------------------------------------------------------------------------------------------------------------------------ Apertures IR-FIX ------------------------------------------------------------------------------------------------------------------------------------ Configurations WFC3/IR ------------------------------------------------------------------------------------------------------------------------------------ Opmodes MULTIACCUM ------------------------------------------------------------------------------------------------------------------------------------ Optional Parameters NSAMP=14, SAMP-SEQ=SPARS50 ------------------------------------------------------------------------------------------------------------------------------------ Special Requirements BETWEEN 31-DEC-2014:00:00:00 AND 31-JAN-2015:00:00:00, PATTERN 1 1 ------------------------------------------------------------------------------------------------------------------------------------ Spectral Elements F110W ------------------------------------------------------------------------------------------------------------------------------------ Target Names CDFS-XT1 ------------------------------------------------------------------------------------------------------------------------------------