10006( 33) - 12/13/04 11:41 - [ 1] PROPOSAL FOR HUBBLE SPACE TELESCOPE OBSERVATIONS ST ScI Use Only ID: 10006 Version: 33 Check-in Date: 13-Dec-2004 16:40:33 1.Proposal Title: Black Hole X-ray Novae in M31 ------------------------------------------------------------------------------------ 2. Proposal For 3. Cycle 4. Parallel Pointing Tolerance GO 12 ------------------------------------------------------------------------------------ 5. Investigators Contact? PI: Dr. Michael R. Garcia Smithsonian Institution Astrophysical Observatory CoI: Dr. Benjamin F. Williams Smithsonian Institution Astrophysical N Observatory CoI: Dr. Albert K. H. Kong Smithsonian Institution Astrophysical N Observatory CoI: Dr. Jon Matthew Miller Smithsonian Institution Astrophysical N Observatory CoI: Dr. Jeffrey E. McClintock Smithsonian Institution Astrophysical N Observatory CoI: Dr. Francis A. Primini Smithsonian Institution Astrophysical N Observatory CoI: Dr. Rosanne Di Stefano Smithsonian Institution Astrophysical N Observatory CoI: Dr. Stephen S. Murray Smithsonian Institution Astrophysical N Observatory ------------------------------------------------------------------------------------ 6. Abstract During A01-3 we found 22 Black Hole X-ray Novae (BHXN) in M31 using Chandra, and with HST (WFPC2) found two optical counterparts. Our results suggest either a surprisingly high ratio of BH to NS binaries, or a surprisingly high duty cycle for BHXN. We propose to continue this program, with the goals of understanding the relative number of BH vs. NS X-ray binaries in the M31 bulge, and determining the orbital period distribution and duty cycles of these BHXN. Continued observations can determine the duty cycle. The new ACS will allow us to go 2 mags deeper than the WFPC2, and could triple the number of optical counterparts and therefore orbital period estimates. M31 is the only galaxy near enough to allow this extragalactic survey for BHXN. ------------------------------------------------------------------------------------ 10006( 33) - 12/13/04 11:41 - [ 2] Observations Description ------------------------ We will use the ACS camera to obtain images of active Black Hole X-ray Novae (BHXNe) in M31. These BHXNe will be identified on Chandra-ACIS observations obtained approximately 1 month prior to each HST observation. We will therefore be splitting up our 10 HST orbits into 10 single-orbit observations to be taken roughly once each month beginning January, 2004, and skipping April and May for solar proximity. The current plan will use the first 5 observations to detect the optical counterparts of 5 BHXNe and the last 5 observations to revisit those 5 BHXN counterparts to ensure that they were optical transients. This plan may be slightly altered over the course of the program depending on when and where the BHXNe are detected. Real Time Justification ----------------------- Our observations must be performed as single-orbit observations at intervals of one per month (except months when the target is sun-blocked) in order to find a counterpart for a new BHXN with each observation. Our preliminary studies indicate that about one new BHXN activates each month. Calibration Justification ------------------------- Additional Comments ------------------- As we will not know the exact location of our target until a Chandra observation is completed each month, we cannot provide final coordinates for our objects until about 3 weeks prior to each observation. As a result, we have currently supplied the coordinates of the nucleus of M31 as a hold position, to be corrected to the final position when we detect the BHXN. These detections will be within 1 degree of the M31 nucleus. ------------------------------------------------------------------------------------ 10006( 33) - 12/13/04 11:41 - [ 3] TARGET LIST Fixed Targets ------------------------------------------------------------------------------------------------------------------------------------ Tar| Target | Target | Target |Coord | Radial | Flux data No | Name | Description | Position |Eqnx | Vel. | ------------------------------------------------------------------------------------------------------------------------------------ 1 M31-BH1 UNIDENTIFIED, X-RAY RA=00H44M6.7000S +/- 1", J2000 V = 25.0+/-5.0 EMITTER DEC=+41D12'19.50" +/- 1" Coordinate Source: Other_Source: Chandra Observation 2 M31-BH2 UNIDENTIFIED, X-RAY RA=00H42M56.0300S +/- 1", J2000 V = 25.0+/-5.0 EMITTER DEC=+41D12'18.97" +/- 1" Coordinate Source: Other_Source: Chandra Observation 3 M31-BH3 UNIDENTIFIED, X-RAY RA=00H42M43.8600S +/- 1", J2000 V = 25.0+/-5.0 EMITTER DEC=+41D16'30.09" +/- 1" Coordinate Source: Other_Source: Chandra Observation 4 M31-BH4 UNIDENTIFIED, X-RAY RA=00H42M33.3900S +/- 1", J2000 V = 25.0+/-5.0 EMITTER DEC=+41D17'43.44" +/- 1" Coordinate Source: Other_Source: Chandra Observation 5 M31-BH5 UNIDENTIFIED, X-RAY RA=00H42M41.5000S +/- 1", J2000 V = 25.0+/-5.0 EMITTER DEC=+41D17'0.00" +/- 1" Coordinate Source: Other_Source: Chandra Observation 6 M31-BH6 UNIDENTIFIED, X-RAY RA=00H43M9.9290S +/- 1", J2000 V = 25.0+/-5.0 EMITTER DEC=+41D23'32.43" +/- 1" Coordinate Source: Other_Source: Chandra Observation 7 M31-BH5- UNIDENTIFIED, X-RAY RA=00H42M41.5000S +/- 1", J2000 V = 25.0+/-5.0 UPDATED EMITTER DEC=+41D17'5.00" +/- 1" Coordinate Source: Other_Source: Chandra Observation 10006( 33) - 12/13/04 11:41 - [ 4] Patterns ------------------------------------------------------------------------------------------------------------------------------------ Pattern_Number: 1 Primary_Pattern Secondary_Pattern Pattern_Type ACS-WFC-DITHER-LINE Pattern_Purpose DITHER Number_Of_Points 2 Point_Spacing 3.011 Line_Spacing Coordinate_Frame POS-TARG Pattern_Orient 85.28 Angle_Between_Sides Center_Pattern NO ------------------------------------------------------------------------------------------------------------------------------------ Pattern_Number: 2 Primary_Pattern Secondary_Pattern Pattern_Type ACS-WFC-DITHER-BOX Pattern_Purpose DITHER Number_Of_Points 4 Point_Spacing 0.265 Line_Spacing 0.187 Coordinate_Frame POS-TARG Pattern_Orient 20.67 Angle_Between_Sides 69.05 Center_Pattern NO ------------------------------------------------------------------------------------------------------------------------------------ 10006( 33) - 12/13/04 11:41 - [ 5] Visit: 01 Visit Priority: Visit Requirements: ORIENT 68.0D TO 74.0 D; BETWEEN 01-DEC-2003:00:00:00 AND 08-DEC- 2003:00:00:00 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| | Requirements ------------------------------------------------------------------------------------------------------------------------------------ 1 M31-BH1 ACS/WFC ACCUM WFC F435W CR-SPLIT=NO,GAIN=2 1 550 S PATTERN 2 1 ------------------------------------------------------------------------------------------------------------------------------------ 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 | ------------------------------------------------------------------------------------------------------------------------------------ M31-BH1 1 ACS/WFC ACCUM WFC F435W 1 none none none 1 N/A M31-BH1 1 ACS/WFC ACCUM WFC F435W 2 none none none 1 N/A M31-BH1 1 ACS/WFC ACCUM WFC F435W 3 none none none 1 N/A M31-BH1 1 ACS/WFC ACCUM WFC F435W 4 none none none 1 N/A 10006( 33) - 12/13/04 11:41 - [ 6] Visit: 02 Visit Priority: Visit Requirements: ORIENT 60.0D TO 60.0 D; BETWEEN 22-DEC-2003:00:00:00 AND 29-DEC- 2003:00:00:00 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| | Requirements ------------------------------------------------------------------------------------------------------------------------------------ 1 M31-BH2 ACS/WFC ACCUM WFC F435W CR-SPLIT=NO,GAIN=2 1 550 S PATTERN 2 1 ------------------------------------------------------------------------------------------------------------------------------------ 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 | ------------------------------------------------------------------------------------------------------------------------------------ M31-BH2 1 ACS/WFC ACCUM WFC F435W 1 none none none 1 N/A M31-BH2 1 ACS/WFC ACCUM WFC F435W 2 none none none 1 N/A M31-BH2 1 ACS/WFC ACCUM WFC F435W 3 none none none 1 N/A M31-BH2 1 ACS/WFC ACCUM WFC F435W 4 none none none 1 N/A 10006( 33) - 12/13/04 11:41 - [ 7] Visit: 03 Visit Priority: Visit Requirements: ORIENT 55.0D TO 55.0 D; BETWEEN 19-JAN-2004:00:00:00 AND 26-JAN- 2004:00:00:00 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| | Requirements ------------------------------------------------------------------------------------------------------------------------------------ 1 M31-BH3 ACS/WFC ACCUM WFC F435W CR-SPLIT=NO,GAIN=2 1 550 S PATTERN 2 1 ------------------------------------------------------------------------------------------------------------------------------------ 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 | ------------------------------------------------------------------------------------------------------------------------------------ M31-BH3 1 ACS/WFC ACCUM WFC F435W 1 none none none 1 N/A M31-BH3 1 ACS/WFC ACCUM WFC F435W 2 none none none 1 N/A M31-BH3 1 ACS/WFC ACCUM WFC F435W 3 none none none 1 N/A M31-BH3 1 ACS/WFC ACCUM WFC F435W 4 none none none 1 N/A 10006( 33) - 12/13/04 11:41 - [ 8] Visit: 04 Visit Priority: Visit Requirements: ORIENT 260.0D TO 260.0 D; BETWEEN 14-JUN-2004:00:00:00 AND 21-JUN- 2004:00:00:00 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| | Requirements ------------------------------------------------------------------------------------------------------------------------------------ 1 M31-BH4 ACS/WFC ACCUM WFC F435W CR-SPLIT=NO,GAIN=2 1 550 S PATTERN 2 1 ------------------------------------------------------------------------------------------------------------------------------------ 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 | ------------------------------------------------------------------------------------------------------------------------------------ M31-BH4 1 ACS/WFC ACCUM WFC F435W 1 none none none 1 N/A M31-BH4 1 ACS/WFC ACCUM WFC F435W 2 none none none 1 N/A M31-BH4 1 ACS/WFC ACCUM WFC F435W 3 none none none 1 N/A M31-BH4 1 ACS/WFC ACCUM WFC F435W 4 none none none 1 N/A 10006( 33) - 12/13/04 11:41 - [ 9] Visit: 05 Visit Priority: Visit Requirements: ORIENT 220.0D TO 220.0 D; BETWEEN 09-AUG-2004:00:00:00 AND 16-AUG- 2004:00:00:00 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| | Requirements ------------------------------------------------------------------------------------------------------------------------------------ 1 M31-BH5 ACS/WFC ACCUM WFC F435W CR-SPLIT=NO,GAIN=2 1 550 S PATTERN 2 1 ------------------------------------------------------------------------------------------------------------------------------------ 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 | ------------------------------------------------------------------------------------------------------------------------------------ M31-BH5 1 ACS/WFC ACCUM WFC F435W 1 none none none 1 N/A M31-BH5 1 ACS/WFC ACCUM WFC F435W 2 none none none 1 N/A M31-BH5 1 ACS/WFC ACCUM WFC F435W 3 none none none 1 N/A M31-BH5 1 ACS/WFC ACCUM WFC F435W 4 none none none 1 N/A 10006( 33) - 12/13/04 11:41 - [ 10] Visit: 06 Visit Priority: Visit Requirements: ORIENT 30.0D TO 40.0 D; BETWEEN 01-MAR-2004:00:00:00 AND 08-MAR- 2004:00:00:00 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| | Requirements ------------------------------------------------------------------------------------------------------------------------------------ 1 M31-BH1 ACS/WFC ACCUM WFC F435W CR-SPLIT=NO,GAIN=2 1 550 S PATTERN 2 1 ------------------------------------------------------------------------------------------------------------------------------------ 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 | ------------------------------------------------------------------------------------------------------------------------------------ M31-BH1 1 ACS/WFC ACCUM WFC F435W 1 none none none 1 N/A M31-BH1 1 ACS/WFC ACCUM WFC F435W 2 none none none 1 N/A M31-BH1 1 ACS/WFC ACCUM WFC F435W 3 none none none 1 N/A M31-BH1 1 ACS/WFC ACCUM WFC F435W 4 none none none 1 N/A 10006( 33) - 12/13/04 11:41 - [ 11] Visit: 07 Visit Priority: Visit Requirements: ORIENT 169.0D TO 169.0 D; BETWEEN 27-SEP-2004:00:00:00 AND 04-OCT- 2004:00:00:00 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| | Requirements ------------------------------------------------------------------------------------------------------------------------------------ 1 M31-BH2 ACS/WFC ACCUM WFC F435W CR-SPLIT=NO,GAIN=2 1 550 S PATTERN 2 1 ------------------------------------------------------------------------------------------------------------------------------------ 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 | ------------------------------------------------------------------------------------------------------------------------------------ M31-BH2 1 ACS/WFC ACCUM WFC F435W 1 none none none 1 N/A M31-BH2 1 ACS/WFC ACCUM WFC F435W 2 none none none 1 N/A M31-BH2 1 ACS/WFC ACCUM WFC F435W 3 none none none 1 N/A M31-BH2 1 ACS/WFC ACCUM WFC F435W 4 none none none 1 N/A 10006( 33) - 12/13/04 11:41 - [ 12] Visit: 08 Visit Priority: Visit Requirements: ORIENT 152.0D TO 152.0 D; BETWEEN 01-NOV-2004:00:00:00 AND 08-NOV- 2004:00:00:00 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| | Requirements ------------------------------------------------------------------------------------------------------------------------------------ 1 M31-BH6 ACS/WFC ACCUM WFC F435W CR-SPLIT=NO,GAIN=2 1 550 S PATTERN 2 1 ------------------------------------------------------------------------------------------------------------------------------------ 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 | ------------------------------------------------------------------------------------------------------------------------------------ M31-BH6 1 ACS/WFC ACCUM WFC F435W 1 none none none 1 N/A M31-BH6 1 ACS/WFC ACCUM WFC F435W 2 none none none 1 N/A M31-BH6 1 ACS/WFC ACCUM WFC F435W 3 none none none 1 N/A M31-BH6 1 ACS/WFC ACCUM WFC F435W 4 none none none 1 N/A 10006( 33) - 12/13/04 11:41 - [ 13] Visit: 09 Visit Priority: Visit Requirements: ORIENT 116.0D TO 116.0 D; BETWEEN 22-NOV-2004:00:00:00 AND 29-NOV- 2004:00:00:00 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| | Requirements ------------------------------------------------------------------------------------------------------------------------------------ 1 M31-BH5-UPD ACS/WFC ACCUM WFC F435W CR-SPLIT=NO,GAIN=2 1 550 S PATTERN 2 1 ATED ------------------------------------------------------------------------------------------------------------------------------------ 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 | ------------------------------------------------------------------------------------------------------------------------------------ M31-BH5-UPDATED 1 ACS/WFC ACCUM WFC F435W 1 none none none 1 N/A M31-BH5-UPDATED 1 ACS/WFC ACCUM WFC F435W 2 none none none 1 N/A M31-BH5-UPDATED 1 ACS/WFC ACCUM WFC F435W 3 none none none 1 N/A M31-BH5-UPDATED 1 ACS/WFC ACCUM WFC F435W 4 none none none 1 N/A 10006( 33) - 12/13/04 11:41 - [ 14] Visit: 10 Visit Priority: Visit Requirements: ORIENT 56.4D TO 57.0 D; BETWEEN 27-DEC-2004:00:00:00 AND 03-JAN- 2005:00:00:00 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| | Requirements ------------------------------------------------------------------------------------------------------------------------------------ 1 M31-BH6 ACS/WFC ACCUM WFC F435W CR-SPLIT=NO,GAIN=2 1 550 S PATTERN 2 1 ------------------------------------------------------------------------------------------------------------------------------------ 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 | ------------------------------------------------------------------------------------------------------------------------------------ M31-BH6 1 ACS/WFC ACCUM WFC F435W 1 none none none 1 N/A M31-BH6 1 ACS/WFC ACCUM WFC F435W 2 none none none 1 N/A M31-BH6 1 ACS/WFC ACCUM WFC F435W 3 none none none 1 N/A M31-BH6 1 ACS/WFC ACCUM WFC F435W 4 none none none 1 N/A 10006( 33) - 12/13/04 11:41 - [ 15] Summary Form for Proposal 10006 Item Used in this proposal ------------------------------------------------------------------------------------------------------------------------------------ Apertures WFC ------------------------------------------------------------------------------------------------------------------------------------ Configurations ACS/WFC ------------------------------------------------------------------------------------------------------------------------------------ Opmodes ACCUM ------------------------------------------------------------------------------------------------------------------------------------ Optional Parameters CR-SPLIT=NO GAIN=2 ------------------------------------------------------------------------------------------------------------------------------------ Proposal Category GO ------------------------------------------------------------------------------------------------------------------------------------ Special Requirements ORIENT 68.0D TO 74.0 D; BETWEEN 01-DEC-2003 00 00 00 AND 08-DEC-2003 00 00 00 PATTERN 2 1 ORIENT 60.0D TO 60.0 D; BETWEEN 22-DEC-2003 00 00 00 AND 29-DEC-2003 00 00 00 ORIENT 55.0D TO 55.0 D; BETWEEN 19-JAN-2004 00 00 00 AND 26-JAN-2004 00 00 00 ORIENT 260.0D TO 260.0 D; BETWEEN 14-JUN-2004 00 00 00 AND 21-JUN-2004 00 00 00 ORIENT 220.0D TO 220.0 D; BETWEEN 09-AUG-2004 00 00 00 AND 16-AUG-2004 00 00 00 ORIENT 30.0D TO 40.0 D; BETWEEN 01-MAR-2004 00 00 00 AND 08-MAR-2004 00 00 00 ORIENT 169.0D TO 169.0 D; BETWEEN 27-SEP-2004 00 00 00 AND 04-OCT-2004 00 00 00 ORIENT 152.0D TO 152.0 D; BETWEEN 01-NOV-2004 00 00 00 AND 08-NOV-2004 00 00 00 ORIENT 116.0D TO 116.0 D; BETWEEN 22-NOV-2004 00 00 00 AND 29-NOV-2004 00 00 00 ORIENT 56.4D TO 57.0 D; BETWEEN 27-DEC-2004 00 00 00 AND 03-JAN-2005 00 00 00 ------------------------------------------------------------------------------------------------------------------------------------ Spectral Elements F435W ------------------------------------------------------------------------------------------------------------------------------------ Target Names M31-BH1 M31-BH2 M31-BH3 M31-BH4 M31-BH5 M31-BH6 M31-BH5-UPDATED ------------------------------------------------------------------------------------------------------------------------------------