Central Bureau for Astronomical Telegrams
IAUC 3331: MXB1837+05; Poss. COMET
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Read IAUC 3332
Circular No. 3331
Central Bureau for Astronomical Telegrams
INTERNATIONAL ASTRONOMICAL UNION
Postal Address: Central Bureau for Astronomical Telegrams
Smithsonian Astrophysical Observatory, Cambridge, MA 02138, U.S.A.
TWX 710-320-6842 ASTROGRAM CAM Telephone 617-864-5758
MXB1837+05
J. A. Hackwell, R. D. Gehrz and G. L. Grasdalen, University of
Wyoming; and L. Cominsky, J. van Paradijs and W. H. G. Lewin, Massachusetts
Institute of Technology, report the detection of an optical
burst (at ~ 3.5-sigma confidence level) from MXB1837+05 (Ser X-1) on
1978 Sept. 7d03h28m47s UT that was simultaneously detected (to within
~ 2 seconds) with an x-ray burst. The optical data were obtained
with the 230-cm telescope of the Wyoming Infrared Observatory
using an EM19658R photometer, broad-band (3200-5400 A) CuSO4
filter and a 5" diaphragm centered on the optical counterpart of
Thorstensen et al. (IAUC 3253). The x-ray observations were made
with SAS 3. The ratio of optical to x-ray energy flux in the burst
was ~ 5 x 10**-6. This result is consistent with the idea that all
the optical light (steady as well as the burst emission) is due to
x-ray heating of a nearby object (presumably the accretion disk)
according to a simple black-body heating model. A similar result was
found for MXB1735-44, from which an x-ray burst has also been
observed simultaneously with an optical burst (Grindlay et al. 1978,
Nature 274, 567). During the 70 min of optical observations of Ser
X-1 two additional optical events were observed similar to the
above. They occurred within 17 seconds of each other at 3h45m48s
and 3h46m05s UT. The SAS-3 Observatory observed Ser X-1 at that
time but did not detect any x-ray enhancements. At present there
is no satisfying explanation for the last two events, but in view
of the very small diaphragm fluctuations due to seeing and guiding
cannot be excluded. However, it is felt that the simultaneous
optical and x-ray bursts are associated. Four x-ray burst sources are
currently identified with faint blue stars: MXB1659-29, MXB1636-53
and the two mentioned above. It is quite possible that optical
flashes will also be detected (simultaneously with x-ray bursts)
from the first two sources. Neither one has yet been studied at a
level of sensitivity comparable to that of MXB1735-44 and Ser X-1.
POSSIBLE COMET
N. S. Chernykh, Crimean Astrophysical Observatory, reports the
discovery of a diffuse comet-like image as follows:
1978 UT R. A. (1950) Decl. m1
Dec. 22.87880 5 06 26.08 +18 54 41.4 16
Daily motion (from a pair of plates): dR.A. = -0m.8, dDecl. = 0'.
1979 February 23 (3331) Brian G. Marsden
Read IAUC 3332
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