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(vsnet-alert 410, Keith Horne)
(J2000 RA=16h 54m 00s Dec=-39 50 45.6)
Please observe with CCD photometers and 1m time resolution to cover 2.6d binary period. The orbital lightcurve will be changing due to X-ray heating, and eclipses may be observed if the accretion disk radius increases during the outburst. The ephemeris for minimum light is
HJD=2449885.592(21) + 2.6212(16)E
(van der Hooft etal 1996 preprint for MNRAS).
Please observe simultaneously with XTE using high-speed photometers on 1m or larger telescopes. Use time resolution at least 1s, but 0.1s or 0.01s or faster if possible. Absolute timing accuracy of at least 0.1s, but 1ms or better if possible. Source may be at V=13, but use white light for maximum count rate, or an R filter may preferred because source probably suffers high reddening E(B-V)=1.0. If simultaneous optical and X-ray lightcurves are obtained, we can use them to look for time delays due to light travel time from X-ray source near black hole to optical light sources being driven by X-ray heating on the accretion disk around the black hole and on the companion star. From time delays measured at different binary phases we can determine the size and inclination of the orbit to constrain the black hole mass, radius of accretion disk, size of companion star, and other details of the structure of the accretion flow.
Scheduled XTE observing times are as follows:
PI: RONALD A. REMILLARD
SOURCE: GRO_J1655-40
TARGET: RA=253.500000, DEC=-39.845798
day 130 = 9 May
1996:130:07:19:00 000074243941 OBSERVATION 10255-01-01-00 START
GOODTIME: 07:32:00 (000074244721) to 07:54:00 (000074246041)
08:20:00 (000074247601) to 08:25:00 (000074247901)
09:02:00 (000074250121) to 09:37:00 (000074252221)
09:56:00 (000074253361) to 10:01:00 (000074253661)
10:38:00 (000074255881) to 11:20:00 (000074258401)
1996:130:11:20:00 000074258401 OBSERVATION 10255-01-01-00 END
1996:130:12:00:00 000074260801 OBSERVATION 10255-01-01-01 START
GOODTIME: 12:30:00 (000074262601) to 12:42:00 (000074263321)
1996:130:12:42:00 000074263321 OBSERVATION 10255-01-01-01 END
1996:130:15:27:00 000074273221 OBSERVATION 10255-01-01-02 START
GOODTIME: 15:57:00 (000074275021) to 16:25:00 (000074276701)
17:02:00 (000074278921) to 18:01:00 (000074282461)
18:51:00 (000074285461) to 19:37:00 (000074288221)
20:37:00 (000074291821) to 21:12:00 (000074293921)
1996:130:21:12:00 000074293921 OBSERVATION 10255-01-01-02 END
1996:130:21:43:00 000074295781 OBSERVATION 10255-01-01-04 START
GOODTIME: 22:20:00 (000074298001) to 22:49:00 (000074299741)
23:59:00 (000074303941) to 00:00:00 (000074304001)
1996:131:00:00:00 000074304001 OBSERVATION 10255-01-01-04 END
day 131 = 10 May
1996:131:06:09:00 000074326141 OBSERVATION 10255-02-01-00 START
GOODTIME: 06:41:00 (000074328061) to 06:49:00 (000074328541)
1996:131:07:01:00 000074329261 OBSERVATION 10255-02-01-00 END
1996:131:08:43:00 000074335381 OBSERVATION 10255-01-02-00 START
GOODTIME: 09:13:00 (000074337181) to 09:38:00 (000074338681)
09:55:00 (000074339701) to 10:01:00 (000074340061)
10:39:00 (000074342341) to 11:22:00 (000074344921)
11:31:00 (000074345461) to 11:38:00 (000074345881)
12:15:00 (000074348101) to 13:14:00 (000074351641)
13:51:00 (000074353861) to 14:50:00 (000074357401)
1996:131:14:50:00 000074357401 OBSERVATION 10255-01-02-00 END
day 132 = 11 May
1996:132:07:08:00 000074416081 OBSERVATION 10255-01-02-01 START
GOODTIME: 07:38:00 (000074417881) to 07:57:00 (000074419021)
08:18:00 (000074420281) to 08:26:00 (000074420761)
09:03:00 (000074422981) to 09:40:00 (000074425201)
09:54:00 (000074426041) to 10:02:00 (000074426521)
10:39:00 (000074428741) to 11:15:00 (000074430901)
1996:132:11:15:00 000074430901 OBSERVATION 10255-01-02-01 END
1996:132:12:33:00 000074435581 OBSERVATION 10255-01-02-04 START
GOODTIME: 13:03:00 (000074437381) to 13:14:00 (000074438041)
13:51:00 (000074440261) to 14:50:00 (000074443801)
15:27:00 (000074446021) to 16:26:00 (000074449561)
1996:132:16:58:00 000074451481 OBSERVATION 10255-01-02-04 END
day 133 = 12 May
1996:133:06:12:00 000074499121 OBSERVATION 10255-01-02-02 START
GOODTIME: 06:41:00 (000074500861) to 06:51:00 (000074501461)
07:28:00 (000074503681) to 07:58:00 (000074505481)
08:17:00 (000074506621) to 08:27:00 (000074507221)
09:04:00 (000074509441) to 09:41:00 (000074511661)
09:53:00 (000074512381) to 10:03:00 (000074512981)
10:40:00 (000074515201) to 11:33:00 (000074518381)
1996:133:11:33:00 000074518381 OBSERVATION 10255-01-02-02 END
1996:133:13:38:00 000074525881 OBSERVATION 10255-01-02-05 START
GOODTIME: 13:51:00 (000074526661) to 14:51:00 (000074530261)
1996:133:15:20:00 000074532001 OBSERVATION 10255-01-02-05 END