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IAUC 5720: 1993G; gamma-RAY BURST; N Cyg 1992

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                                                  Circular No. 5720
Central Bureau for Astronomical Telegrams
INTERNATIONAL ASTRONOMICAL UNION
Postal Address: Central Bureau for Astronomical Telegrams
Smithsonian Astrophysical Observatory, Cambridge, MA 02138, U.S.A.
Telephone 617-495-7244/7440/7444 (for emergency use only)
TWX 710-320-6842 ASTROGRAM CAM     EASYLINK 62794505
MARSDEN@CFA or GREEN@CFA (.SPAN, .BITNET or .HARVARD.EDU)


SUPERNOVA 1993G IN NGC 3690
     A. V. Filippenko, T. Matheson, B. Leibundgut and L. C. Ho,
University of California at Berkeley, report that CCD spectra (range
300-1000 nm) obtained on Mar. 13 with the Shane 3-m reflector at the
Lick Observatory reveal that SN 1993G (cf. IAUC 5718, 5719) is of type
II, within a few weeks of maximum brightness.  The prominent H-alpha
emission line, which peaks near 657 nm, is broad (FWHM approximately
10 000 km/s) and asymmetric, but the corresponding absorption is weak.
H-beta, H-gamma and H-delta, by contrast, exhibit deep absorption.
Narrow H-alpha emission from a faint underlying H II region appears at
663 nm (cz = 3070 km/s).
     B. Schmidt and R. Kirshner, Center for Astrophysics, report that
observations on Mar. 15 by S. Raychaudhury and G. Bernstein with the
Multiple-Mirror Telescope confirm the supernova to be of type II.
H-alpha, H-beta and He I (587.6 nm) show P-Cyg profiles, and absorption
lines of Fe II (492.4, 501.8 and 516.9 nm) give a photospheric
expansion of approximately 600 km/s.


gamma-RAY BURST
     A. Goldwurm, M. C. Schmitz-Fraysse, E. Churazov, M. Gilfanov, on
behalf of the SIGMA/Granat team (Service d'Astrophysique du CEA, Saclay;
Centre d'Etude Spatiale des Rayonnements, Toulouse; Space Research
Institute, Moscow), report: "The SIGMA telescope on board the Granat
Observatory detected a gamma-ray burst on Mar. 10.30576 UT.  The event
lasted about 20 s and was detected in the 35-400-keV energy range through
an interruption of the passive shield acting as a collimator.  The
localization process is based on a maximum-likelihood method yielding
a signal-to-noise ratio of 16.  The 1-sigma error box of the burst is
approximately diamond-shaped, the positions of the corners being
R.A. = 19h16m01s, Decl. = -49d24'; 19h04m37s, -52d23'; 18h49mn59s, -54d01';
18h58m19s, -52d07' (equinox 1950.0)."


NOVA CYGNI 1992
     Further visual magnitude estimates: Feb. 8.98 UT, 10.7 (B. H.
Granslo, Fjellhamar, Norway); 13.97, 10.7 (H. Dahle, Oslo, Norway);
19.04, 10.8 (Granslo); 23.75, 10.5 (M. Tombelli, Montelupo, Italy);
Mar. 8.48, 11.4 (W. G. Dillon, Missouri City, TX); 13.16, 11.2 (A.
Boattini, Florence, Italy).


1993 March 16                  (5720)              Brian G. Marsden

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