9087( 16) - 07/30/02 11:14 - [ 1] PROPOSAL FOR HUBBLE SPACE TELESCOPE OBSERVATIONS ST ScI Use Only ID: 9087 Version: 16 Check-in Date: 30-Jul-2002 11:13:40 1.Proposal Title: Black Hole X-ray Transients and X-ray Binaries in M31 ------------------------------------------------------------------------------------ 2. Proposal For 3. Cycle GO 10 ------------------------------------------------------------------------------------ 4. Investigators Contact? PI: Michael Garcia Smithsonian Institution Astrophysical Observatory CoI: Dr. Stephen Murray Smithsonian Astrophysical Observatory N CoI: Dr. Rosanne DiStefano Smithsonian Astrophysical Observatory N CoI: Dr. Frank Primini Smithsonian Astrophysical Observatory N CoI: Dr. Andrew King Leicester University N ------------------------------------------------------------------------------------ 5. Abstract As part of the Chandra Guaranteed Time Observations (GTO) program, we are searching M31 for x-ray transients. A complimentary GO program to study supersoft x-ray sources in M31 has recently been approved, and it will significantly expand our ability to find x-ray transients in M31. The x-ray properties of these transient sources (spectra, variability) allow us to determine whether the accreting object is a black hole or a neutron star. We propose HST observations of these x-ray transients to determine the nature of the mass-losing star. Massive stars will show little (<2 mag) change in their UV luminosities during outbursts, while low-mass stars will show large (>5 mag) changes in their UV luminosities. By determining the nature of the primary (accreting) and secondary stars in these x-ray transients, we will have the first dataset that will allow the evolution of black hole and neutron star binaries to be studied in an external galaxy. As >70\ transients in the Milky Way (MW) contain black hole primaries, we expect that a major result will be an understanding of the formation of stellar mass black holes in another galaxy. Recent HST/DD observations of one M31 x-ray transient demonstrate that these observations are entirely feasible. ------------------------------------------------------------------------------------ 9087( 16) - 07/30/02 11:14 - [ 2] Observations Description ------------------------ In order to estimate the magnitude of a BH XRT in M31, we scale the outburst magnitudes of BH XRTs in the Galaxy to the distance and reddening of M31. V404 Cyg was one of the most optically luminous XRT in our galaxy, with an outburst V=12.7 at a distance of 3.5 kpc and a reddening of A(v) = 3. Scaling the observed photometry to the 700 kpc distance and A(v) = 0.23 of M31, we would expect U=21.7. A0620-00 was one of the least luminous XRTs, with an outburst V=11.1 at a 1.2 kpc distance and A(v) = 1.1. Scaling to M31, we would expect U=23.0. Scaling the observed properties of 0535-668, a Be transient found in the LMC, we would expect U~ 22 in outburst. In outburst, the U-band light from an XRT with a low-mass secondary is dominated by reprocessing of x-rays. The fact that the peak L_X in post-minimum XRTs is perhaps 10* lower than BH XRTs then implies that the peak U-mag will be ~ 2.5 mags fainter. The quiescent mag should be on the order of the secondary magnitude, so might also be slightly fainter than a BH XRT or NS XRT due to the extreme evolution of the post- minimum secondary. Thus these XRT should be distinguished from Be-type transients by the larger amplitude of the U-band outburst, and should be distinguished from NS XRTs or BH XRTs by their ~ 10* smaller peak x-ray luminosity and perhaps slightly lower U-band maximum. We propose a series of short WFPC2 (PC Mode, 34'' FOV, 0.046'' pixels) observations. Because XRTs are UV-bright and the M31 background is low when using the PC mode, we have chosen the F336W (U-band) filter. In what follows, we assume that a BH XRT will have magnitudes that are the mean of the V404 Cyg and A0620-00 magnitudes above. We assume PM XRTs will be 2.5 magnitudes fainter. The exposure times are as follows: U = F336W, 3 x 1800 seconds: For a BH XRT, the ETC predicts S/N~ 25, and for the fainter post-minimum XRT, S/N~ 3. Combining the three images will allow rejection of cosmic rays and increases the effective S/N for the post- minimum XRT to ~ 5. We scaled the Fesen etal BG to the F336W bandpass, and predict 100 e-/exposure from the M31 background. The total exposure time is 5400sec. Assuming 50\ viewing efficiency, we assume 2 full orbits will be needed. We propose repeating exactly the same exposures approximately three months later, as the typical XRT in the M31 will have decayed by then. Real Time Justification ----------------------- We previously applied to the Chandra AO2 TAC to carry out this program under the joint Chandra/HST proposal program. We were not awarded time, and were surprised when HST personnel supporting the Chandra review informed us that HST did not intend for Chandra GTO programs to have access to this jointly allocated time. Furthermore, the Chandra TAC responded to us with: ``Was this really a vehicle for getting the HST time? If the latter was the case, it seemed to be more appropriate for the proposers to request HST time directly and ask for early implementation of the proposal.'' We therefore are applying directly for HST time and are not specifically applying for any of the HST time set aside for joint HST/Chandra programs. Should the HST TAC look favorably upon our proposal, we request they assign the proposal to whatever program they deem appropriate. We point out that this may be the only foreseeable opportunity to carry out a joint HST/Chandra survey of M31. There is no guarantee that Chandra will continue observing M31, either under the GO or GTO program. Chandra is the only x-ray observatory that has the spatial resolution to resolve the central regions of M31. All other flying and even planned missions have much lower spatial resolution, and therefore will not be able to carry out this study. The Chandra AO2/GTO observations consist of 6 ACIS pointings, each 5ks duration, nominally centered on the M31 nucleus. These pointings will occur roughly every two months. We request 2 orbits of 9087( 16) - 07/30/02 11:14 - [ 3] simultaneous (+/- 4 day) HST observations for each of these, to be followed by 2 more orbits at the same position roughly 3 months later. The typical decay time of XRTs in the MW is roughly ~ 2 months, so this observation plan will allow one observation near the peak, and one well into the decay. While the nominal pointing position is the nucleus, the FOV of ACIS (16' * 16') is significantly larger than the WFPC2 (~ 0.5' * 0.5'). When interesting transients are found with ACIS, we propose to change the HST pointing position to cover them. Followup observations at this pointing position (2 HST orbits) would occur roughly 3 months later. The changes to the HST pointing position would occur >~x 1 month before observations (ie, they would be triggered by the previous ACIS observation), so should be compatible with the HST scheduling cycle. In addition to the ACIS pointings at the nucleus, we will survey the entire 3 degrees of M31 a few times with the HRC with sufficient sensitivity to detect XRT. Should these observations reveal appropriate XRTs away from the nucleus, we would move next available ACIS (and HST) observations to this location. The Chandra AO2/GO observations consist of 3 repeated ACIS pointings, each 15ks duration, centered on the positions of 3 supersoft x-ray sources within M31. The current Chandra plan is that the repeated observations will be separated by ~ 2 months, and that observations at each position will be staggered so the observations occur over the entire 1 year AO2 cycle. As above, we request 2 orbits of simultaneous (+/- 4 day) HST observations for each Chandra observation, to be followed by 2 more orbits roughly 2 months later. We are putting in a request to the Chandra team to split each 15ks Chandra observation into 3 5ks observations in order to better search for XRT. This would roughly triple the number of transients we could find and follow, and we would therefore select only the most promising of these to followup with our requested HST time. We point out that similar requests for changes to Chandra observations have been honored in the past, and that acceptance of this HST proposal would provide very strong incentive to make these changes. Each HST observation consists of 2 orbits, so our total request is for 6 * (2 + 2) = 24 orbits for the GTO program, and 3 * 3 * (2+2) = 36 orbits for the GO program, for a total of 60 orbits. Flexibility: We are presented with an exciting opportunity to simultaneously use the complementary unique capabilities of HST and Chandra to develop the statistics of black hole and neutron star populations in another galaxy. This years Chandra observations are specifically designed to detect transients, and likely represent a one-time opportunity for substantial numbers of simultaneous HST and Chandra observations. Although we strongly favor a program of the size described above, we note that our science goals are robust against small cuts in this 60 orbit request. We would simply follow-up fewer transients. We estimate that sixty orbits would allow us to follow up 15 transients. Forty orbits would allow us to follow-up 10, a number which is often cited as a minimum for statistical studies. An allocation of 20 orbits would allow us to study 5, which would be sufficient to determine if the transients in M31 had gross properties similar to those in the MW, but insufficient to carry out studies of the various classes of transients. Calibration Justification ------------------------- Additional Comments ------------------- Note that we request that the first visit to each target be within +/- 4 days of simultaneous with Chandra. Followup visits do NOT have this constraint. While we believe these dates are also suitable for Chandra, the Chandra dates have not yet been locked in. We will request that they be fixed to the HST schedule, but there is a small possibility some of the dates will not be 9087( 16) - 07/30/02 11:14 - [ 4] suitable. If that does occur, we may request the HST dates to be moved. It should be possible to know if there are any conflict before March 31 (perhaps before Feb 29 ------------------------------------------------------------------------------------ 9087( 16) - 07/30/02 11:14 - [ 5] TARGET LIST Fixed Targets ------------------------------------------------------------------------------------------------------------------------------------ Tar| Target | Target | Target |Coord | Radial | Flux data No | Name | Description | Position |Eqnx | Vel. | ------------------------------------------------------------------------------------------------------------------------------------ 1 M31-T1 EXT-STAR RA=00H 42M 34.896S +/- .10S, J2000 V = 24.0+/-1.0 DEC=40D 57' 21.01" +/-0.01D B-V = 0.0+/-1.0 Coordinate Source: OTHER_SOURCE Comments: transient 2 M31-T2 EXT-STAR RA=00H 43M 08.5S +/- .10S, J2000 V = 24.0+/-1.0 DEC=41D 18' 20" +/- 0.01D B-V = 0.0+/-1.0 Coordinate Source: OTHER_SOURCE Comments: This is a holding position at the of a bright transient we recently found near the M32 nucleus, to be updated >4 weeks before the exposure with the position of an X-ray transient found within M31 via our Chandra monitoring program. 3 M31-T3 EXT-STAR RA=00H 43M 5.55S +/- .2S, J2000 V = 24.0+/-1.0 DEC=41D 17' 3.30" +/- 0.02D B-V = 0.0+/-1.0 Coordinate Source: OTHER_SOURCE Comments: This is t3, which got up to 3e38 erg/sec 4 M31-T4 EXT-STAR RA=00H 43M 09.797S +/- .05S, J2000 V = 24.0+/-1.0 DEC=41D 19' 00.72" +/-0.01D B-V = 0.0+/-1.0 Coordinate Source: OTHER_SOURCE Comments: This is o-16, which was seen with Einstein and early Chandra obs, but then dissappeared in 2002 chandra obs. it was 3e37 in early chandra obs. 5 M31-T5 EXT-STAR RA=00H 41M 54.691S +/- .05S, J2000 V = 24.0+/-1.0 DEC=40D 56' 47.80" +/- 0.01D B-V = 0.0+/-1.0 Coordinate Source: OTHER_SOURCE Comments: This is a holding position at the M31 nucleus, to be updated > 4 weeks before the exposure with the position of an X-ray transient found within M31 via our Chandra monitoring program. 6 M31-T6 EXT-STAR RA=00H 41M 54.673S +/- .05S, J2000 V = 24.0+/-1.0 DEC=40D 56' 47.5" +/- 0.01D B-V = 0.0+/-1.0 Coordinate Source: OTHER_SOURCE Comments: This is a holding position at the M31 nucleus, to be updated > 4 weeks before the exposure with the position of an X-ray transient found within M31 via our Chandra monitoring program. 9087( 16) - 07/30/02 11:14 - [ 6] Patterns ------------------------------------------------------------------------------------------------------------------------------------ Pattern_Number: 11 Primary_Pattern Secondary_Pattern Pattern_Type ACS-WFC-DITHER-LINE Pattern_Purpose DITHER Number_Of_Points 2 Point_Spacing 3.011 Coordinate_Frame POS-TARG Pattern_Orient 85.28 Center_Pattern NO ------------------------------------------------------------------------------------------------------------------------------------ Pattern_Number: 13 Primary_Pattern Secondary_Pattern Pattern_Type ACS-WFC-DITHER-LINE Pattern_Purpose DITHER Number_Of_Points 3 Point_Spacing 0.138 Coordinate_Frame POS-TARG Pattern_Orient 32.99 Center_Pattern NO ------------------------------------------------------------------------------------------------------------------------------------ 9087( 16) - 07/30/02 11:14 - [ 7] Visit: 01 Visit Priority: Visit Requirements: BETWEEN 02-JUL-2001 AND 09-JUL-2001 On Hold Comments: Additional Comments: First visit to M31-t1 Exposures ------------------------------------------------------------------------------------------------------------------------------------ Exposure| Target |Instr | Oper. | Aper |Spectral|Central| Optional |Num| Time | Special Number | Name |Config| Mode |or FOV |Element |Waveln.| Parameters |Exp| | Requirements ------------------------------------------------------------------------------------------------------------------------------------ 10 M31-T1 WFPC2 IMAGE PC1 F336W CR-SPLIT=NO 8 500 S ------------------------------------------------------------------------------------------------------------------------------------ 9087( 16) - 07/30/02 11:14 - [ 8] Visit: 02 Visit Priority: Visit Requirements: BETWEEN 01-OCT-2001 AND 15-OCT-2001 On Hold Comments: Additional Comments: Follow-up visit to M31-t1 Exposures ------------------------------------------------------------------------------------------------------------------------------------ Exposure| Target |Instr | Oper. | Aper |Spectral|Central| Optional |Num| Time | Special Number | Name |Config| Mode |or FOV |Element |Waveln.| Parameters |Exp| | Requirements ------------------------------------------------------------------------------------------------------------------------------------ 10 M31-T1 WFPC2 IMAGE PC1 F336W CR-SPLIT=NO 8 500 S Comments: three months (+/- 1 week) from first visit at t1 ------------------------------------------------------------------------------------------------------------------------------------ 9087( 16) - 07/30/02 11:14 - [ 9] Visit: 03 Visit Priority: Visit Requirements: BETWEEN 27-AUG-2001 AND 03-SEP-2001 On Hold Comments: Additional Comments: First visit to M31-t2 Exposures ------------------------------------------------------------------------------------------------------------------------------------ Exposure| Target |Instr | Oper. | Aper |Spectral|Central| Optional |Num| Time | Special Number | Name |Config| Mode |or FOV |Element |Waveln.| Parameters |Exp| | Requirements ------------------------------------------------------------------------------------------------------------------------------------ 10 M31-T2 WFPC2 IMAGE PC1 F336W CR-SPLIT=NO 8 500 S ------------------------------------------------------------------------------------------------------------------------------------ 9087( 16) - 07/30/02 11:14 - [ 10] Visit: 04 Visit Priority: Visit Requirements: BETWEEN 02-DEC-2001 AND 09-DEC-2001 On Hold Comments: Additional Comments: Follow up visit to M31-t2 Exposures ------------------------------------------------------------------------------------------------------------------------------------ Exposure| Target |Instr | Oper. | Aper |Spectral|Central| Optional |Num| Time | Special Number | Name |Config| Mode |or FOV |Element |Waveln.| Parameters |Exp| | Requirements ------------------------------------------------------------------------------------------------------------------------------------ 10 M31-T2 WFPC2 IMAGE PC1 F336W CR-SPLIT=NO 8 500 S Comments: follow up visit to M31-t2 at 3 months +/- 1 week ------------------------------------------------------------------------------------------------------------------------------------ 9087( 16) - 07/30/02 11:14 - [ 11] Visit: 05 Visit Priority: Visit Requirements: BETWEEN 05-NOV-2001 AND 12-NOV-2001 On Hold Comments: Additional Comments: First visit to M31-t3 Exposures ------------------------------------------------------------------------------------------------------------------------------------ Exposure| Target |Instr | Oper. | Aper |Spectral|Central| Optional |Num| Time | Special Number | Name |Config| Mode |or FOV |Element |Waveln.| Parameters |Exp| | Requirements ------------------------------------------------------------------------------------------------------------------------------------ 10 M31-T3 WFPC2 IMAGE PC1 F336W CR-SPLIT=NO 8 500 S ------------------------------------------------------------------------------------------------------------------------------------ 9087( 16) - 07/30/02 11:14 - [ 12] Visit: 06 Visit Priority: Visit Requirements: BETWEEN 04-FEB-2002 AND 11-FEB-2002 On Hold Comments: Additional Comments: Follow-up visit to M31-t3 at T+3months Exposures ------------------------------------------------------------------------------------------------------------------------------------ Exposure| Target |Instr | Oper. | Aper |Spectral|Central| Optional |Num| Time | Special Number | Name |Config| Mode |or FOV |Element |Waveln.| Parameters |Exp| | Requirements ------------------------------------------------------------------------------------------------------------------------------------ 10 M31-T3 WFPC2 IMAGE PC1 F336W CR-SPLIT=NO 8 500 S ------------------------------------------------------------------------------------------------------------------------------------ 9087( 16) - 07/30/02 11:14 - [ 13] Visit: 07 Visit Priority: Visit Requirements: BETWEEN 07-JAN-2002 AND 14-JAN-2002 On Hold Comments: Additional Comments: First visit to M31-t4 Exposures ------------------------------------------------------------------------------------------------------------------------------------ Exposure| Target |Instr | Oper. | Aper |Spectral|Central| Optional |Num| Time | Special Number | Name |Config| Mode |or FOV |Element |Waveln.| Parameters |Exp| | Requirements ------------------------------------------------------------------------------------------------------------------------------------ 10 M31-T4 WFPC2 IMAGE PC1 F336W CR-SPLIT=NO 8 500 S ------------------------------------------------------------------------------------------------------------------------------------ 9087( 16) - 07/30/02 11:14 - [ 14] Visit: 08 Visit Priority: Visit Requirements: BETWEEN 25-Jun-2002 AND 30-Jun-2002 On Hold Comments: Additional Comments: was Followup visit to M31-t4, now use ACS to confirm t3 Exposures ------------------------------------------------------------------------------------------------------------------------------------ Exposure| Target |Instr | Oper. | Aper |Spectral|Central| Optional |Num| Time | Special Number | Name |Config| Mode |or FOV |Element |Waveln.| Parameters |Exp| | Requirements ------------------------------------------------------------------------------------------------------------------------------------ 10 M31-T3 ACS/WF ACCUM WFC1 F435W CR-SPLIT=NO 2 400 S PATTERN 11 10 C Comments: no need to be simultaneous with Chandra, since this transient is long gone... but the dissappearance of the uv counterpart needs to be confirmed with acs/wfc ------------------------------------------------------------------------------------------------------------------------------------ 11 M31-T3 ACS/WF ACCUM WFC1 F435W CR-SPLIT=NO 1 500 S C ------------------------------------------------------------------------------------------------------------------------------------ 20 M31-T3 ACS/WF ACCUM WFC1 F435W CR-SPLIT=NO 2 350 S PATTERN 13 20 C ------------------------------------------------------------------------------------------------------------------------------------ 9087( 16) - 07/30/02 11:14 - [ 15] Visit: 09 Visit Priority: Visit Requirements: BETWEEN 19-Aug-2002 AND 26-Aug-2002 On Hold Comments: Additional Comments: First visit to M31-t5; position tbd by chandra obsid 2901, scheduled july8- 15 2002 Exposures ------------------------------------------------------------------------------------------------------------------------------------ Exposure| Target |Instr | Oper. | Aper |Spectral|Central| Optional |Num| Time | Special Number | Name |Config| Mode |or FOV |Element |Waveln.| Parameters |Exp| | Requirements ------------------------------------------------------------------------------------------------------------------------------------ 10 M31-T5 ACS/WF ACCUM WFC1 F435W CR-SPLIT=NO 2 400 S PATTERN 11 10 C ------------------------------------------------------------------------------------------------------------------------------------ 11 M31-T5 ACS/WF ACCUM WFC1 F435W CR-SPLIT=NO 1 500 S C ------------------------------------------------------------------------------------------------------------------------------------ 20 M31-T5 ACS/WF ACCUM WFC1 F435W CR-SPLIT=NO 2 350 S PATTERN 13 20 C ------------------------------------------------------------------------------------------------------------------------------------ 9087( 16) - 07/30/02 11:14 - [ 16] Visit: 10 Visit Priority: Visit Requirements: BETWEEN 24-Nov-2002 AND 01-Dec-2002 On Hold Comments: Additional Comments: Followup visit to M31-t5, linke to chandra obsid 2900 Exposures ------------------------------------------------------------------------------------------------------------------------------------ Exposure| Target |Instr | Oper. | Aper |Spectral|Central| Optional |Num| Time | Special Number | Name |Config| Mode |or FOV |Element |Waveln.| Parameters |Exp| | Requirements ------------------------------------------------------------------------------------------------------------------------------------ 10 M31-T5 ACS/WF ACCUM WFC1 F435W CR-SPLIT=NO 2 400 S PATTERN 11 10 C ------------------------------------------------------------------------------------------------------------------------------------ 11 M31-T5 ACS/WF ACCUM WFC1 F435W CR-SPLIT=NO 1 500 S C ------------------------------------------------------------------------------------------------------------------------------------ 20 M31-T5 ACS/WF ACCUM WFC1 F435W CR-SPLIT=NO 2 350 S PATTERN 13 20 C ------------------------------------------------------------------------------------------------------------------------------------ 9087( 16) - 07/30/02 11:14 - [ 17] Visit: 11 Visit Priority: Visit Requirements: BETWEEN 08-Jul-2002 AND 15-Jul-2002 On Hold Comments: Additional Comments: First visit to M31-t6; position tbd by chandra obsid 2898, june 3-10 2002 Exposures ------------------------------------------------------------------------------------------------------------------------------------ Exposure| Target |Instr | Oper. | Aper |Spectral|Central| Optional |Num| Time | Special Number | Name |Config| Mode |or FOV |Element |Waveln.| Parameters |Exp| | Requirements ------------------------------------------------------------------------------------------------------------------------------------ 10 M31-T6 ACS/WF ACCUM WFC1 F435W CR-SPLIT=NO 2 400 S PATTERN 11 10 C ------------------------------------------------------------------------------------------------------------------------------------ 11 M31-T6 ACS/WF ACCUM WFC1 F435W CR-SPLIT=NO 1 500 S C ------------------------------------------------------------------------------------------------------------------------------------ 20 M31-T6 ACS/WF ACCUM WFC1 F435W CR-SPLIT=NO 2 350 S PATTERN 13 20 C ------------------------------------------------------------------------------------------------------------------------------------ 9087( 16) - 07/30/02 11:14 - [ 18] Visit: 12 Visit Priority: Visit Requirements: BETWEEN 01-Dec-2002 AND 08-Dec-2002 On Hold Comments: Additional Comments: Followup visit to M31-t6 Exposures ------------------------------------------------------------------------------------------------------------------------------------ Exposure| Target |Instr | Oper. | Aper |Spectral|Central| Optional |Num| Time | Special Number | Name |Config| Mode |or FOV |Element |Waveln.| Parameters |Exp| | Requirements ------------------------------------------------------------------------------------------------------------------------------------ 10 M31-T6 ACS/WF ACCUM WFC1 F435W CR-SPLIT=NO 2 400 S PATTERN 11 10 C ------------------------------------------------------------------------------------------------------------------------------------ 11 M31-T6 ACS/WF ACCUM WFC1 F435W CR-SPLIT=NO 1 500 S C ------------------------------------------------------------------------------------------------------------------------------------ 20 M31-T6 ACS/WF ACCUM WFC1 F435W CR-SPLIT=NO 2 350 S PATTERN 13 20 C ------------------------------------------------------------------------------------------------------------------------------------ 9087( 16) - 07/30/02 11:14 - [ 19] Summary Form for Proposal 9087 Item Used in this proposal ------------------------------------------------------------------------------------------------------------------------------------ Apertures PC1 WFC1 ------------------------------------------------------------------------------------------------------------------------------------ Configurations WFPC2 ACS/WFC ------------------------------------------------------------------------------------------------------------------------------------ Opmodes IMAGE ACCUM ------------------------------------------------------------------------------------------------------------------------------------ Optional Parameters CR-SPLIT=NO ------------------------------------------------------------------------------------------------------------------------------------ Proposal Category GO ------------------------------------------------------------------------------------------------------------------------------------ Special Requirements BETWEEN 02-JUL-2001 AND 09-JUL-2001 BETWEEN 01-OCT-2001 AND 15-OCT-2001 BETWEEN 27-AUG-2001 AND 03-SEP-2001 BETWEEN 02-DEC-2001 AND 09-DEC-2001 BETWEEN 05-NOV-2001 AND 12-NOV-2001 BETWEEN 04-FEB-2002 AND 11-FEB-2002 BETWEEN 07-JAN-2002 AND 14-JAN-2002 BETWEEN 25-Jun-2002 AND 30-Jun-2002 PATTERN 11 10 PATTERN 13 20 BETWEEN 19-Aug-2002 AND 26-Aug-2002 BETWEEN 24-Nov-2002 AND 01-Dec-2002 BETWEEN 08-Jul-2002 AND 15-Jul-2002 BETWEEN 01-Dec-2002 AND 08-Dec-2002 ------------------------------------------------------------------------------------------------------------------------------------ Spectral Elements F336W F435W ------------------------------------------------------------------------------------------------------------------------------------ Target Names M31-T1 M31-T2 M31-T3 M31-T4 M31-T5 M31-T6 ------------------------------------------------------------------------------------------------------------------------------------