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IAUC 6343: C/1996 B2; GRO J1744-28

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                                                  Circular No. 6343
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/1996 B2 (HYAKUTAKE)
     R. M. West, European Southern Observatory (ESO), writes:  "A
series of forty-four 2-sec exposures in B, V, and R was obtained
under excellent conditions (seeing 0".7-0".8) on Mar. 19.33-19.40
UT with the ESO 3.5-m New Technology Telescope (+ SUSI camera;
observers O. Hainaut and R. West).  A comparison of two series of
twelve R-frames each, at mean epochs Mar. 19.342 and 19.363 (i.e.,
a 30-min interval), by means of averaged, radially normalized
frames, shows substantial morphological changes (on a scale of
arcseconds) of the dust jets within 10" from the peak of light.  In
addition to a well-indicated clockwise rotation of about 20 deg,
there are also changes apparent in the jet structure.  There is
also an unchanged straight ion tail at p.a. 276 deg, noticeable at
0".7 (115 km projected) from the peak of light in both frames.
These images have been placed on the ESO World Wide Web homepage
(http://www.eso.org/educnpubrelns/comet-hyakutake.html)."
     Naked-eye m1, coma-diameter, and tail-length estimates:  Mar.
17.35 UT, 3.4, --, > 6 deg (J. V. Scotti, Kitt Peak, AZ); 18.58,
2.5, 50', 10 deg (P. Camilleri, Cobram, Victoria, Australia);
19.22, 2.6, 1.1 deg, -- (J. E. Bortle, Stormville, NY); 19.34, 2.0,
about 80', 20 deg (C. S. Morris, Whitaker Peak, CA); 19.38, 2.5,
1.2 deg, 15 deg (A. Hale, Cloudcroft, NM); 19.73, 2.5, --, -- (A.
Beresford, Adelaide, South Australia).


GRO J1744-28
     L. Bouchet, J. Paul, M. Gilfanov, and R. Sunyaev, on behalf of
the SIGMA/Granat team (Centre d'Etude Spatiale des Rayonnements,
Toulouse; Service d'Astrophysique du CEA, Saclay; Space Research
Institute, Moscow), report: "The SIGMA telescope onboard the Granat
satellite started a new campaign of observing the galactic-center
region on Mar. 15.62 UT, continuing until Mar. 29.  In the first
observation (effective duration 30 000 s), GRO J1744-28 was
detected in the images up to about 75 keV at R.A. = 17h41m22s, Decl.
= -28o45'.6 (equinox 1950.0; uncertainty +/- 3'), only 1'.5 from the
reported XTE position (IAUC 6309).  Preliminary analysis gave the
total (variable + continuous) flux of about 150 mCrab in the band
40-75 keV, with a very soft spectrum.  Also, 1E 1740.7-2942 was
detected (well separated from GRO J1744-28) at the about 3-sigma
level in the same band.  The two sources GRO J1744-28 and 1E
1740.7-2942 were also detected in a subsequent observation (duration
80 000 s) beginning on Mar. 17, which has shown a decline of the
flux of GRO J1744-28 by a factor of about 1.5 in the energy range
40-75 keV."

                      (C) Copyright 1996 CBAT
1996 March 19                  (6343)            Daniel W. E. Green

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