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IAUC 6868: XTE J0421+560; GRB 980329; N Sgr 1998

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                                                 Circular No. 6868
Central Bureau for Astronomical Telegrams
Mailstop 18, Smithsonian Astrophysical Observatory, Cambridge, MA 02138, U.S.A.
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XTE J0421+560
     M. Orlandini, D. Dal Fiume, and F. Frontera, Istituto
Tecnologie e Studio Radiazioni Extraterrestri, CNR, Bologna; L. A.
Antonelli, BeppoSAX Science Data Center, Rome; L. Piro, Istituto
Astrofisica Spaziale, CNR, Rome; and A. N. Parmar, Space Science
Department, ESTEC, report:  "On Apr. 3.2 UT, BeppoSAX observed XTE
J0421+560 with its Narrow Field Instruments.  The source position
as determined by LECS and MECS is R.A. = 4h19m46s.0, Decl. =
+55o59'24" (equinox 2000.0; error radius 50"), consistent with the
Marshall et al. position (IAUC 6857) and the CI Cam position (IAUC
6862).  The source was fading during the 45 000-s observation; a
fit with an exponential decay law gives an e-folding time of 0.89
+/- 0.02 day.  We observe a prominent iron line in emission at 6.7
keV with an equivalent width of 670 eV, as well as other low-
energy features.  The 2-10- and 15-100-keV fluxes averaged over the
whole observation are 1.16 x 10E-9 and 1.58 x 10E-10 erg cmE-2
sE-1, respectively."

GRB 980329
     I. A. Smith, Rice University; and R. P. J. Tilanus, Joint
Astronomy Centre, report on behalf of the James Clerk Maxwell Telescope
(JCMT) GRB collaboration:  "We used the JCMT (+ SCUBA submillimeter
continuum bolometer array) to observe the variable radio source VLA
J0702+3850 proposed by Taylor et al. (see IAUC 6864) as the radio
afterglow to GRB 980329.  On Apr. 5.2 UT, we detected a source at
850 microns with a preliminary flux density of 5 +/- 1.5 mJy.  This
source was confirmed on Apr. 6.2 with a flux density of 4 +/- 1.2
mJy, resulting in an average of 4.5 +/- 1 mJy over the two days.
The source is present in all our separate integrations, making us
confident that it is real.  A hint of a fading trend appears to be
confirmed by observations on Apr. 7.2, when the (preliminary) 850-
micron flux density was 2 +/- 0.8 mJy.  The source was not detected
at 450 microns, with a preliminary rms of 10.0 mJy averaged over
the first two days.  Assuming these fluxes are due to the burst
counterpart, they should represent 'clean' measures of its
intensity, unaffected by scintillation and extinction."

     Visual magnitude estimates:  Apr. 1.73 UT, 9.4 (F. Farrell,
Christies Beach, S. Australia); 4.199, 9.0 (A. Pereira, Cabo da
Roca, Portugal); 5.165, 9.2 (P. Schmeer, Bischmisheim, Germany);
6.203, 9.7 (Pereira).

                      (C) Copyright 1998 CBAT
1998 April 7                   (6868)            Daniel W. E. Green

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