Central Bureau for Astronomical Telegrams
IAUC 3117: X-RAY BURSTS; X Per; 1976b
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Circular No. 3117
Central Bureau for Astronomical Telegrams
INTERNATIONAL ASTRONOMICAL UNION
Postal Address: Central Bureau for Astronomical Telegrams
Smithsonian Astrophysical Observatory, Cambridge, MA 02138, U.S.A.
Cable Address: SATELLITES, NEWYORK Telex: 921428
Telephone: (617) 864-5758
X-RAY BURSTS
J. A. Hoffman, H. Marshall and W. H. G. Lewin, SAS-3 Group,
Massachusetts Institute of Technology, observed the rapid burster
MXB1730-335 between Sept. 27.267 and Oct. 3.420 UT. The burst frequency
varied from ~ 250 bursts per hour to ~ 50 bursts per hour;
individual bursts lasted from ~ 3 to ~ 10 seconds. In addition to
the several thousands of bursts that were detected daily from the
rapid burster, 11 bursts were detected from MXB1728-34 and 17 were
observed from a region within 10' of the rapid burster. These 17
bursts, definitely not from MXB1728-34, were distinctly different
from the repetitive bursts of the rapid burster. They occurred at
intervals that declined from ~ 3.5 hours on Sept. 28 (rms jitter ~
10 percent) to 2.9 hours on Oct. 2 (rms jitter ~ 8 percent). In
the range 2-6 keV the 17 bursts lasted typically ~ 30 seconds; in
the range 8-19 keV they lasted ~ 15 seconds. It is believed that
the 17 bursts come from the rapid burster, but the possibility that
they come from a new source within ~ 10' of it cannot be excluded.
Other x-ray observatories are urged to search for these bursts, especially
after the rapid burster has ceased to produce bursts in
rapid succession (which is expected to happen in a few weeks).
X PERSEI
P. V. Kal'v, Tallinn Observatory, reports that X Per has recently
brightened by 0.24 magnitude in V and 0.17 magnitude in B.
PERIODIC COMET KOPFF (1976b)
The following precise positions have been reported:
1977 UT R. A. (1950) Decl. Observer
June 23.31111 0 54 41.55 + 2 19 43.2 McCrosky
July 27.86265 1 36 13.48 + 4 45 58.3 Candy
Sept.12.82911 1 39 31.33 + 2 39 58.0 Jekabsons
13.82708 1 38 53.10 + 2 34 01.2 Candy
R. E. McCrosky (Harvard College Observatory, Agassiz Station).
155-cm reflector. Measurer: J. H. Bulger.
M. P. Candy and P. Jekabsons (Perth Observatory, Bickley). 33-cm
astrograph.
1977 October 6 (3117) Brian G. Marsden
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