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IAUC 6560: C/1995 O1; 1997Z; NO X-RAY TRANSIENT NEAR SMC X-1

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                                                 Circular No. 6560
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/cfa/ps/cbat.html
Phone 617-495-7244/7440/7444 (for emergency use only)

     J. Lecacheux, Observatoire de Paris-Meudon; L. Jorda, Max-
Planck-Institut fur Aeronomie; and F. Colas, Bureau des Longitudes,
write:  "CCD images of comet C/1995 O1, obtained with the 1.05-m
telescope at Pic du Midi Observatory under good-seeing conditions
on twelve nights between Jan. 12 and Feb. 10, show a dust jet of
maximum length about 8000 km (6"); the length and p.a. of the jet
change within 1.75 hr of observation and from one night to another,
revealing the nuclear spin -- the extreme position angles of 170
and 230 deg being observed on Feb. 4.28 and 10.23 UT.  We infer a
possible rotation period of 11.47 +/- 0.05 hr from the comparison
of images obtained during different nights.  This jet produces a
fan of aperture 70 deg in the southwestern quadrant with concentric
dust shells (first reported by O. Lardiere at Haute Provence
Observatory).  These shells are separated by 12 000 km (9") and a
preliminary analysis show that they expand at about 0.3 km/s
(0".75/hr), in agreement with a spin period of about 12 hr.  The
aperture of the fan and the appearance of the jet suggest that the
source is at a latitude of -60 deg, probably illuminated at all
times, the south pole being in view at p.a. 200 deg.  The remaining
linear structures might be the boundaries of fans, as suggested by
Sekanina and Boehnhardt (IAUC 6542)."
     Naked-eye total-magnitude and tail-length estimates: Feb. 6.22
UT, 1.8, 2 deg (O. Skilbrei, Hoenefoss, Norway); 9.27, 1.8, 4.5 deg
(A. Pereira, Cabo da Roca, Portugal); 11.21, 1.5, -- (R. J. Bouma,
Groningen, The Netherlands); 13.21, 1.3, 15 deg (P. Candy, Viterbo,
Italy); 16.22, 1.2, 5 deg (J. Carvajal, Teruel, Spain); 17.48, 1.1,
6 deg (G. Kronk, Troy, IL).

     F. Winkler, A. Clocchiatti, and R. Covarrubias, Cerro Tololo
Interamerican Observatory, report a precise position for SN 1997Z
from an image obtained with the 0.9-m telescope:  R.A. =
10h29m06s.65, Decl. = -44o39'35".2 (equinox 2000.0; rms 1"), which
is 62".7 west and 11".3 north of a nearby star of mag V = 14.3.

     G. Clark, Massachusetts Institute of Technology, reports: "The
transient x-ray pulsar near SMC X-1, reported on IAUC 6444, does
not exist.  It was an artifact caused by a processing error in the
received ROSAT data and is not present in the reprocessed data now
in the HEASARC archive."

                      (C) Copyright 1997 CBAT
1997 February 17               (6560)            Daniel W. E. Green

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