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Date: Wed, 18 Aug 93 16:07:34 MST
From: rmw@altair.lowell.edu (R. Mark Wagner)
Subject: GRO J0422+32
Dear Colleagues,
As many of you are aware, a new outburst of the soft X-ray transient
GRO J0422+32 was reported by Alex Filippenko and Tom Matheson on August
13th (IAUC 5842). Subsequent photometry reported in the IAUC's and
this bulletin board indicated that J0422+32 brightened from about 19th
magntitude in late July to about 15th magnitude on August 13th. Tim
Naylor reported to me this morning that his photometry using the 1-m
telescope at La Palma on 1993 Aug 18.2 gives V = 15.5.
Fortuitously, we (myself, Sumner Starrfield, Chris Shrader, and Bob
Hjellming) had an approved ROSAT AO4 program to observe J0422+32
scheduled to begin Aug 17th UT to study the X-ray spectra of quiescent
soft X-ray transient black hole candidates. Even though J0422+32 has
entered a new outburst, our ROSAT observations will continue over the
next 6 days. J0422+32 was detected by ROSAT at a level of about 1 PSPC
count/sec at our first pointing on Aug 17th. The times of our ROSAT
observations are given below:
UT Date UT start UT start Duration (seconds)
======= ======== ======== ==================
930817. 16861. 04:41:01 2339.00
930819. 56363. 15:39:23 2400.00
930820. 56664. 15:44:24 1740.00
930821. 15557. 04:19:17 2038.00
930821. 21299. 05:54:59 2011.00
930821. 49637. 13:47:17 2323.00
930821. 55664. 15:27:44 2386.00
930822. 15208. 04:13:28 1982.00
930822. 21006. 05:50:06 1614.00
930822. 44114. 12:15:14 1141.00
930822. 55407. 15:23:27 2220.00
930823. 14838. 04:07:18 1962.00
930823. 20616. 05:43:36 1554.00
930823. 26346. 07:19:06 1269.00
930823. 32091. 08:54:51 1104.00
930823. 43636. 12:07:16 1244.00
930823. 49376. 13:42:56 1894.00
930823. 55106. 15:18:26 2149.00
There is some concern that a new and more intense outburst could occur at
any time that might harm the PSPC detector aboard ROSAT. I would appreciate
receiving any reports that place the visual magnitude of J0422+32 above
about 14 magnitude so that the we can inform the ROSAT Observatory of the
change in source intensity prior to their next observation.
Sincerely yours,
R. Mark Wagner
Department of Astronomy
Ohio State University
rmw@lowell.edu
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