Central Bureau for Astronomical Telegrams
IAUC 3025: N Sge 1977; gamma-RAY BURSTS; MXB1637-53
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Read IAUC 3026
Circular No. 3025
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
NOVA SAGITTAE 1977
S. W. Milbourn, British Astronomical Association, cables that
John G. Hosty, Huddersfield, has discovered a nova, as follows:
1977 UT R. A. (1950) Decl. mv
Jan. 7.73 19 37.1 +18 02 7.2
The nova has been confimed by G. M. Hurst, Northampton, who gave
the magnitude as 7.6 on Jan. 9.76 UT.
gamma-RAY BURSTS
R. W. Klebesadel, Los Alamos Scientific Laboratory, reports
that three major peaks of intensity were observed on 1976 Dec. 20
with a total fluence of ~ 2 x l0**-3 erg cm**-2 at energies > 150 keV.
Onset times were 17h38m32s, 17h38m40s and 17h38m52s UT. The location
of the source is currently resolved to a band +/- 10o wide extending
from R.A. = 22h.1, Decl. = -65o to R.A. = 23h.6, Decl. = -12o. The bursts
may represent a recurrence of the source GRB 72-6, observed by
Apollo 16 on 1972 Apr. 27 within ~ 10o of R.A. = 23h.0, Decl. = -68o.
MXB1637-53
J. A. Hoffman, J. Doty and W. H. G. Lewin, Massachusetts
Institute of Technology, report that SAS 3 has detected nine x-ray
bursts from MXB1637-53 at R.A. = 16h37m.1, Decl. = -53o41' (equinox 1950.0);
the radius of the error circle (95-percent confidence) is 6'. This
burst source is almost certainly the strong, steady x-ray source 3U
1636-53, which lies 2'.4 away; it is probably the same burst source
discovered by OSO 8 (IAUC 3000). During Jan. 1-4 the average burst
interval was ~ 11h, although two bursts were separated by only 2h.6.
The average peak burst intensity (3-12 keV) was about twice that of
the Crab, and the average burst duration was less than 10s. The
precise 3U position for the steady source (confirmed by SAS 3)
makes it an excellent candidate for study at other wavelengths.
During the same period observations were also made of the steady
source MX1608-52, which has been proposed as another x-ray burst
source; no bursts were detected from this source on this occasion.
1977 January 11 (3025) Brian G. Marsden
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