12751( 3) - 18-Apr-2012 10:28:17 - [ 1] HUBBLE SPACE TELESCOPE OBSERVING PROGRAM 12751 Version: 3 Check-in Time: 18-Apr-2012 10:28:17 STScI Edit Number: 0 Title The Spectral Energy Distribution of a Very Faint X-ray Transient ------------------------------------------------------------------------------------ Type Cycle GO 19 ------------------------------------------------------------------------------------ Investigators Contact? PI: Dr. Craig Heinke University of Alberta CoI: Dr. Haldan N Cohn Indiana University System N CoI: Dr. Phyllis M. Lugger Indiana University System N ------------------------------------------------------------------------------------ Abstract Very faint X-ray transient accretion states (peak L X < 10^36 ergs/s) are hard to explain with standard theories of disk instabilities. The unusual globular cluster transient M15 X-3 has only been seen at Lx~6e33 and at 2-6e31 ergs/s. We aim to determine the nature of the companion star through near-simultaneous Chandra and HST imaging, measuring its X-ray spectrum and optical colors. ------------------------------------------------------------------------------------ Observations Description ------------------------ We plan to use our one HST orbit to obtain images of the central region of M15 with the WFC3 camera in F438W (B), F606W (broad V) and F814W (I), within 1 week before or after our Chandra observation, to identify the nature of M15 X-3Ős secondary. To ensure the highest spatial resolution, we will take 4 observations in each filter, using a box dither pattern. We aim for a uniform SNR of 23 for M15 X-3 (F555W=22.2) in all filters. In order to fit the 12 exposures into a single orbit it is necessary to use the 1k*1k subarray. We note that this still gives us well-dithered deep imaging of the full core of M15, enabling a variety of ancillary science. Real Time Justification ----------------------- Calibration Justification ------------------------- Additional Comments ------------------- We request that the HST observations be carried out within 1 week before or after our Chandra observation. ------------------------------------------------------------------------------------ 12751( 3) - 18-Apr-2012 10:28:17 - [ 2] TARGET LIST Fixed Targets ------------------------------------------------------------------------------------------------------------------------------------ Tar| Target | Target | Target |Coord | Radial | Flux data No | Name | Description | Position |Eqnx | Vel. | ------------------------------------------------------------------------------------------------------------------------------------ 1 M15 STELLAR CLUSTER, RA=21H29M58.2000S +/- 0.1", J2000 V = 15 +/- 1 GLOBULAR CLUSTER DEC=+12D09'53.80" +/- 0.1" Reference Frame: ICRS Comments: This object was generated by the targetselector and retrieved from the SIMBAD database. ------------------------------------------------------------------------------------------------------------------------------------ 12751( 3) - 18-Apr-2012 10:28:17 - [ 3] 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 ------------------------------------------------------------------------------------------------------------------------------------ 12751( 3) - 18-Apr-2012 10:28:17 - [ 4] Visit: 02 Visit Requirements: ORIENT 346D TO 60 D; ORIENT 76D TO 150 D; ORIENT 166D TO 240 D; ORIENT 256D TO 330 D On Hold Comments: Additional Comments: This visit should be scheduled within one week before or after the Chandra observation for this joint Chandra/HST program. The Orient requirements ensure that the diffraction spikes of a nearby bright star do not fall on the key program star. Revised following suggestion by Peter McCullough, April 16, 2012. Exposures ------------------------------------------------------------------------------------------------------------------------------------ Exp | Target | Instr | Oper. | Aper |Spectral|Central| Optional |Num| Time | Special Num | Name | Config | Mode | or FOV |Element |Waveln.| Parameters |Exp| | Requirements ------------------------------------------------------------------------------------------------------------------------------------ 1 M15 WFC3/UVI ACCUM UVIS2-C1K F438W 1 340 S PATTERN 1 1 S 1C-SUB ------------------------------------------------------------------------------------------------------------------------------------ 2 M15 WFC3/UVI ACCUM UVIS2-C1K F606W 1 47 S PATTERN 1 2 S 1C-SUB Comments: Increased by 1 s ------------------------------------------------------------------------------------------------------------------------------------ 3 M15 WFC3/UVI ACCUM UVIS2-C1K F814W 1 83 S PATTERN 1 3 S 1C-SUB ------------------------------------------------------------------------------------------------------------------------------------ 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 | ------------------------------------------------------------------------------------------------------------------------------------ M15 1 WFC3/UVI ACCUM UVIS2-C1 F438W 1 none none none 1 N/A S K1C-SUB M15 1 WFC3/UVI ACCUM UVIS2-C1 F438W 2 none none none 1 N/A S K1C-SUB M15 1 WFC3/UVI ACCUM UVIS2-C1 F438W 3 none none none 1 N/A S K1C-SUB M15 1 WFC3/UVI ACCUM UVIS2-C1 F438W 4 none none none 1 N/A S K1C-SUB M15 2 WFC3/UVI ACCUM UVIS2-C1 F606W 1 none none none 1 N/A S K1C-SUB M15 2 WFC3/UVI ACCUM UVIS2-C1 F606W 2 none none none 1 N/A S K1C-SUB M15 2 WFC3/UVI ACCUM UVIS2-C1 F606W 3 none none none 1 N/A S K1C-SUB M15 2 WFC3/UVI ACCUM UVIS2-C1 F606W 4 none none none 1 N/A S K1C-SUB M15 3 WFC3/UVI ACCUM UVIS2-C1 F814W 1 none none none 1 N/A S K1C-SUB M15 3 WFC3/UVI ACCUM UVIS2-C1 F814W 2 none none none 1 N/A S K1C-SUB M15 3 WFC3/UVI ACCUM UVIS2-C1 F814W 3 none none none 1 N/A S K1C-SUB 12751( 3) - 18-Apr-2012 10:28:17 - [ 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 | ------------------------------------------------------------------------------------------------------------------------------------ M15 3 WFC3/UVI ACCUM UVIS2-C1 F814W 4 none none none 1 N/A S K1C-SUB 12751( 3) - 18-Apr-2012 10:28:17 - [ 6] Summary Form for Proposal 12751 Item Used in this proposal ------------------------------------------------------------------------------------------------------------------------------------ Apertures UVIS2-C1K1C-SUB ------------------------------------------------------------------------------------------------------------------------------------ Configurations WFC3/UVIS ------------------------------------------------------------------------------------------------------------------------------------ Opmodes ACCUM ------------------------------------------------------------------------------------------------------------------------------------ Optional Parameters ------------------------------------------------------------------------------------------------------------------------------------ Special Requirements ORIENT 166D TO 240 D, ORIENT 256D TO 330 D, ORIENT 346D TO 60 D, ORIENT 76D TO 150 D, PATTERN 1 1, PATTERN 1 2, PATTERN 1 3 ------------------------------------------------------------------------------------------------------------------------------------ Spectral Elements F438W, F606W, F814W ------------------------------------------------------------------------------------------------------------------------------------ Target Names M15 ------------------------------------------------------------------------------------------------------------------------------------