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IAUC 6472: C/1991 A2; GAMMA-RAY BURST 960720; 1996 PW

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                                                  Circular No. 6472
Central Bureau for Astronomical Telegrams
INTERNATIONAL ASTRONOMICAL UNION
Postal Address: Central Bureau for Astronomical Telegrams
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)
Phone 617-495-7244/7440/7444 (for emergency use only)


COMET C/1991 A2 (ARAI)
     K. Dennerl, J. Englhauser, and J. Trumper, Max-Planck-Institut
fur Extraterrestrische Physik, Garching, communicate:  "X-ray
emission from comet C/1991 A2 (= 1991b = 1990 XXVI) was detected in
data obtained with the ROSAT Position Sensitive Proportional
Counter during the all-sky survey.  The comet was observed from
1990 Nov. 18.09 to 21.43 UT (Delta = 1.2 AU, r = 1.5 AU), six weeks
before it was discovered (IAUC 5157), when it would have had
projected visual m1 about 12 (or fainter) and would be optically
the faintest comet ever detected in x-rays."


GAMMA-RAY BURST 960720
     D. A. Frail, National Radio Astronomy Observatory; S. R.
Kulkarni, California Institute of Technology; L. Piro, E. Costa, M.
Feroci, and M. Cinti, Istituto Astrofisica Spaziale, CNR, Frascati;
F. Frontera, D. Dal Fiume, L. Nicastro, M. Orlandini, and G.
Pizzichini, Istituto Tecnologie e Studio delle Radiazioni
Extraterrestri, CNR, Bologna; J. Heise and R. Jager, Space Research
Organization of the Netherlands, Utrecht; and H. Muller, Beppo-SAX
Scientific Data Center, Rome, report:  "We made radio observations
at the position of the gamma-ray burst detected by Beppo-SAX on
July 20 (IAUC 6467) using the Very Large Array (VLA) in Socorro at
a wavelength of 20 cm.  Images taken on Sept. 7.98 and 9.06 UT were
compared with an image taken more than one year earlier as part of
the VLA All-Sky Survey by Condon et al. (http://www.cv.nrao.edu/
~jcondon/nvss.html).  There are no radio sources in the 10' error
circle above a 4-sigma level of 2 mJy in either the preburst or
postburst images.  This includes the position of the ROSAT x-ray
source reported by Boller and Voges (IAUC 6469).  There are five
radio sources just outside the error circle but none shows any
signs of unusual variability."


1996 PW
     S. Mottola and U. Carsenty, DLR German Aerospace Establishment,
Berlin, write:  "CCD photometry of 1996 PW, obtained during Sept.
7-10 with the Bochum 0.60-m telescope at the European Southern
Observatory, reveals a rotational lightcurve with two maxima and
two minima.  We determined an unambiguous rotation period of 35.5
hr, an amplitude of 0.40 mag, and a reduced magnitude V(alpha = 8.5
deg) = 14.69."

                      (C) Copyright 1996 CBAT
1996 September 11              (6472)            Daniel W. E. Green

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