Central Bureau for Astronomical Telegrams

Central Bureau for Astronomical Telegrams -- Image credits

IAUC 2953: X-RAY BURSTS; V616 Mon; V1500 Cyg

The following International Astronomical Union Circular may be linked-to from your own Web pages, but must not otherwise be redistributed (see these notes on the conditions under which circulars are made available on our WWW site).

Read IAUC 2952 SEARCH Read IAUC 2954
IAUC number 

                                                  Circular No. 2953
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
Western Union: RAPID SATELLITE CAMBMASS


X-RAY BURSTS
     R. H. Becker, S. H. Pravdo, P. J. Serlemitsos and J. H. Swank,
Goddard Space Flight Center, report that the cosmic x-ray spectroscopy
experiment on OSO-8 has detected two x-ray bursts from a region
of the sky centered on R.A. = 18h36m, Decl. = -22o.7 (equinox 1950.0).
The bursts occurred on Mar. 27.581 and 29.437 UT, each with risetimes
< 2s and decay times ~ 15s.  Neither of the bursts could have
come from any of the previously identified burst sources.  If the
two bursts have a common origin  the implied error box has corners
at R.A. = 18h47m.4, Decl. = -18o20'; 18h26m.2, -27o17'; 18h14m.2, -19o19';
18h59m.2, -25o43'.  The box contains the source 3U 1832-23.  The
bursts had a maximum intensity of ~ 40 percent of the Crab between
2 and 20 keV.  These results are based on the 5 percent of the data
from this period that is now available.

     J. Hoffman, Massachusetts Institute of Technology, informs us
that his final statement on IAUC 2946 applies only to the burst
sources within 1o of the galactic center.  The SAS-3 Group observed
MXB1730-335 (cf. IAUC 2922) for some five hours around Apr. 27.85
UT and found no burst activity to a level ~< 0.08 of the count rate
at burst maximum observed previously.


V616 MONOCEROTIS
     D. Ya. Martynov, Sternberg Astronomical Institute, communicates
the following photographic magnitudes by S. Yu. Shugarov:
Mar. 29, 15.7; 31, 15.8; Apr. 1, 16.1; 2, 16.5; 3, 16.9; 4, 17.2;
and a visual magnitude: Apr. 23, 17.5.  Photoelectric observation
by V. M. Lyutyj: Mar. 31, V = 14.72, B-V = +1.02, U-B = -0.76.


V1500 CYGNI
     Further to IAUC 2926 and 2938, R. Wood and P. J. Andrews,
Royal Greenwich Observatory, write that a V exposure with the 66-cm
refractor does show a star surrounded by a pronounced ring some 15"
in diameter.  Considering that the refractor has a steep color
curve away from the B region, they suggest that the 'star' is the
in-focus image of the continuum near 5600 A, while the 'ring' is
merely an out-of-focus image of the very strong emission at 5007 A.

     Visual magnitude estimates by R. Lukas, Wilhelm Foerster
Observatory: Apr. 18.95 UT, 10.9; 29.93, 11.2; May 9.92, 11.4.


1976 May 18                    (2953)              Brian G. Marsden

Read IAUC 2952 SEARCH Read IAUC 2954

Our Web policy. Index to the CBAT/MPC/ICQ pages.

Valid HTML 4.01!