Central Bureau for Astronomical Telegrams

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IAUC 6912: 1998ce; GRB 980519

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                                                 Circular No. 6912
Central Bureau for Astronomical Telegrams
Mailstop 18, Smithsonian Astrophysical Observatory, Cambridge, MA 02138, U.S.A.
IAUSUBS@CFA.HARVARD.EDU or FAX 617-495-7231 (subscriptions)
URL http://cfa-www.harvard.edu/iau/cbat.html
Phone 617-495-7244/7440/7444 (for emergency use only)

SUPERNOVA 1998ce IN MCG -4-24-19
     S. Woodings, R. Martin, and A. Williams report their discovery
of an apparent supernova (R about 16) on an image taken through
thin cloud on May 19.50 UT with the Perth-Lowell 0.61-m reflector
in the course of the Perth Astronomy Research Group's automated
supernova search (confirmed with an image taken on May 21.7).  J.
Biggs and A. Verveer provide the following position for SN 1998ce
from unfiltered CCD images obtained around May 21.461 with the
0.25-m Mike Candy Telescope at Perth:  R.A. = 10h10m34s.70 +/-
0s.02, Decl. = -25o49'30".8 +/- 0".3 (equinox 2000.0; mag 16.0),
which is about 9" west and 8" south of the center of MCG -4-24-19.
The last image of the field was taken on May 3, with no object
visible to mag about 19.

GRB 980519
     L. Nicastro, Istituto di Fisica Cosmica ed Applicazioni
all'Informatica, CNR, Palermo; L. A. Antonelli, BeppoSAX Science
Data Center, Rome; G. Celidonio, M. R. Daniele, C. De Libero, and
G. Spoliti, BeppoSAX Science Operation Center, Rome; L. Piro,
Istituto Astrofisica Spaziale, CNR, Rome; and E. Pian, Istituto di
Tecnologie e Studio delle Radiazioni Extraterrestri, CNR, Bologna,
on behalf of the BeppoSAX team, report:  "The BeppoSAX Wide Field
Camera error box of GRB 980519 (IAUC 6910) was observed with the
BeppoSAX Narrow Field Instruments starting on May 19.920 UT (9.7 hr
after the burst).  A previously unknown x-ray source,
1SAX J2322.3+7716, was detected by the LECS and MECS instruments
(units 2 and 3) at R.A. = 23h22m22s, Decl. = +77o16'.1 (equinox
2000.0; error radius 50").  This position is 1'.2 from the centroid
of the WFC position and is compatible with the optical transient
detected by Jaunsen et al. (GCN 78; R.A. = 23h22m21s.46, Decl. =
+77o15'43".0, equinox 2000.0; I about 19.5 on May 19.87).  The
source exhibits a non-monotonic decay, steeper during the first 4-5
hr of the 1.2-day observation.  The average count rate of the first
4 hr is 0.007 +/- 0.001 counts/s (2-10 keV) in the two MECS units,
corresponding to (3.8 +/- 0.6) x 10E-13 erg cmE-2 sE-1 (assuming a
Crab-like energy spectrum).  At the end of the observation, the
source had faded by a factor of about 4.  These results strongly
suggest that 1SAX J2322.3+7716 is the x-ray afterglow of GRB

                      (C) Copyright 1998 CBAT
1998 May 22                    (6912)            Daniel W. E. Green

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