Central Bureau for Astronomical Telegrams
IAUC 4575: X-RAY OUTBURST; 1987A; DO Dra
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Read IAUC 4576
Circular No. 4575
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 617-495-7244/7440/7444
MARSDEN or GREEN@CFA.BITNET MARSDEN or GREEN@CFAPS2.SPAN
X-RAY OUTBURST
F. Makino and the Ginga Team, Institute of Space and
Astronautical Science, Tokyo, telex: "An x-ray outburst from the
region of the sky including Cep X-4 (Ulmer et al. 1973, Ap.J. 184,
L117) has been detected since Mar. 18 with the all-sky monitor
aboard Ginga. The x-ray intensity obtained by scanning with the
large-area counters on Mar. 27 was 0.06 and 0.03 cts s-1 cm-2 at 1-4
and 9-18 keV, respectively. The source is located on a line (of
width 0.1 deg) connecting the points R.A. = 21h36m, Decl. = +57.1
deg and R.A. = 21h39m, Decl. = +56.8 deg. The hardness ratio is
similar to that of a hard transient. The x-ray intensity increased
to about 100 mCrab on Mar. 30."
SUPERNOVA 1987A IN THE LARGE MAGELLANIC CLOUD
P. Bouchet and J. Danziger, European Southern Observatory,
report: "Infrared observations of SN 1987A were carried out on Mar.
29 and 30 at La Silla using the 2.2-m telescope, equipped with an
f/35 wobbling secondary and the ESO infrared photometer. CVF
spectra were obtained in the region 8-13 micrometers. Measurements
of the line at 10.53 micrometers show that it has decreased in flux
by a factor of two since our observation late in 1987 Nov. If this
line is due to the Co II fine structure transition, then the
estimated mass of Co II (and hence, according to the best models, of
all the Co) on Mar. 30 was 0.0023 solar mass. (The theoretical
models would give a value of 0.0020 solar mass after 400 days, if
the amount originally produced had been 0.07 solar mass.) We found
the same good agreement between observation and theory for our
measurements in 1987 Nov. (i.e., after 280 days), when the measured
mass of Co II (assuming again that the line has been identified
correctly) was 0.044 solar mass. The observations do not allow any
definitive velocity determination."
Further visual magnitude estimates by A. C. Beresford,
Adelaide, South Australia: Mar. 22.51 UT, 7.2; 24.54, 7.1; 31.60,
7.4.
DO DRACONIS
Visual magnitude estimates: Mar. 29.44 UT, [13 (T. Kato, Kyoto,
Japan); 31.01, 10.3 (G. Dyck, North Dartmouth, MA); 31.43, 10.3
(Kato).
1988 April 1 (4575) Brian G. Marsden
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