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IAUC 7160: GRB 990510; 1999ca

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                                                  Circular No. 7160
Central Bureau for Astronomical Telegrams
INTERNATIONAL ASTRONOMICAL UNION
Mailstop 18, Smithsonian Astrophysical Observatory, Cambridge, MA 02138, U.S.A.
IAUSUBS@CFA.HARVARD.EDU or FAX 617-495-7231 (subscriptions)
BMARSDEN@CFA.HARVARD.EDU or DGREEN@CFA.HARVARD.EDU (science)
URL http://cfa-www.harvard.edu/iau/cbat.html  ISSN 0081-0304
Phone 617-495-7244/7440/7444 (for emergency use only)


GRB 990510
     M. Dadina, L. Di Ciolo, and A. Coletta, BeppoSAX, Rome; P.
Soffitta and M. Feroci, Istituto Astrofisica Spaziale, CNR, Rome;
J. Heise and E. Kuulkers, Space Research Organization of the
Netherlands (SRON), Utrecht; J. M. Muller, BeppoSAX, Rome, and
SRON; and F. Frontera and L. Amati, Istituto Tecnologie e Studio
Radiazioni Extraterrestri, CNR, Bologna, write:  "The BeppoSAX
Gamma Ray Burst Monitor observed a gamma-ray burst starting on May
10.36743 UT.  A preliminary analysis reveals a duration of about 80
s and a multipeak structure, with a peak intensity of 3100 counts/s
in the energy band 40-700 keV.  The burst was also detected in Wide
Field Camera unit 2 with comparable duration, a peak intensity of
about 4.3 Crab and an average intensity of 0.7 Crab (2-28 keV).
The position of the x-ray counterpart is R.A. = 13h38m06s, Decl. =
-80o29'.5 (equinox 2000.0), with an error radius of 3'.  A follow-up
observation with BeppoSAX narrow-field instruments is in progress."


SUPERNOVA 1999ca IN NGC 3120
     F. Patat, European Southern Observatory (ESO); J. Maza,
Universidad de Chile; S. Benetti, Telescopio Nazionale Galileo,
Centro Galileo Galilei, Santa Cruz de La Palma; and E. Cappellaro,
Padova Observatory, write:  "We have observed SN 1999ca (cf. IAUC
7158) with the ESO New Technology Telescope (+ EMMI; range 340-1000
nm, resolution 1.0 nm) on May 7.05 UT at La Silla.  A full
reduction of the CCD spectrogram shows that this is a type-II
supernova around one month after maximum light.  H-alpha, H-beta,
H-gamma, and H-delta, superimposed on a continuum that peaks around
550 nm, are clearly visible.  The H-alpha line is quite asymmetric,
with possible unresolved structures, and its P-Cyg absorption is
very weak.  Besides the Balmer series, the most prominent features
are identified as Ca II, Ba II, Fe I, Na I, and Ca II.  The
expansion velocities, deduced from the absorption minima, are 6800,
7600, and 6400 km/s for Ca II H and K, Na I D, and H-alpha,
respectively.  Two unresolved absorptions of Na I D are clearly
visible; one is at the parent-galaxy rest-frame velocity (2791
km/s; Theureau et al. 1998, A.Ap. Suppl. 130, 333), while the other
absorption most likely originates in the Milky Way.  The total
equivalent widths are 0.27 and 0.13 nm for the two Na features,
respectively."

                      (C) Copyright 1999 CBAT
1999 May 10                    (7160)            Daniel W. E. Green

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