Circular No. 6851
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)
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Phone 617-495-7244/7440/7444 (for emergency use only)


GRB 980326
     G. Celidonio and A. Coletta, BeppoSAX Science Operation Center,
Telespazio, Rome; M. Feroci, L. Piro, and P. Soffitta, Istituto
Astrofisica Spaziale, CNR, Rome; J. in 't Zand, Space Research
Organization of the Netherlands (SRON), Utrecht; J. Muller,
BeppoSAX Science Data Center, Rome and SRON, and E. Palazzi,
Istituto Tecnologie e Studio Radiazioni Extraterrestri, Bologna,
report: "The BeppoSAX Gamma Ray Burst Monitor was triggered on Mar.
26.888125 UT, coincident with BATSE trigger 6660.  A quick-look
analysis shows a single-peak gamma-ray burst lasting about 5 s and
having a peak flux of 500 counts/s in the range 40-700 keV.  The
gamma-ray burst was also detected by unit 1 of the Wide Field
Cameras (WFC1) with a peak flux of about 4 Crab in the range 2-26
keV.  The position from a quick-look analysis is R.A. = 8h36m26s,
Decl. = -18o53'.0 (equinox 2000.0).  The accuracy of the satellite
attitude was not optimum, and we adopt an error radius of 8'.  Due
to sun constraints, the GRB location cannot be presently observed
by BeppoSAX Narrow Field Instruments."


COMET 55P/TEMPEL-TUTTLE
     P. Lamy, Laboratoire d'Astronomie Spatiale, and his team
report the detection of the nucleus of comet 55P with the Hubble
Space Telescope (+ WFPC2) on Jan. 9 at Delta = 0.46 AU:  "After
removing the faint contribution of the coma to the central pixels,
the magnitude of the nucleus was R = 16.62, showing no variation
over 10 hr.  For a geometric albedo of 0.04 and a phase coefficient
of 0.04 mag/deg, the mean effective radius is 1.8 km, the largest
uncertainty coming from the phase law.  The red color of the
nucleus is characterized by a normalized reflectivity gradient of
0.16 percent/nm."
     Visual m_1 estimates:  Mar. 1.75 UT, 8.7 (V. Znojil, Brno,
Czech R., 25x100 binoculars); 18.24, 9.7: (N. Biver, Honolulu, HI,
0.26-m reflector).


NOVA SAGITTARII 1998
     B. A. Skiff, Lowell Observatory, reports that examination of
the original Palomar Sky Survey prints show nothing definite at the
location of N Sgr 1998, indicating a lower limit on the outburst
amplitude of at least 11 (and perhaps 12) magnitudes.
     Additional visual magnitude estimates:  Mar. 25.12 UT, 8.4 (L.
Kiss, Szeged, Hungary); 26.141, 8.1 (K. Hornoch, Lelekovice, Czech
Republic); 26.66, 8.2 (F. Farrell, Christies Beach, S. Australia);
27.17, 8.7 (A. Baransky, Kiev, Ukraine); 27.215, 8.4 (A. Pereira,
Cabo da Roca, Portugal).

                      (C) Copyright 1998 CBAT
1998 March 27                  (6851)            Daniel W. E. Green