Central Bureau for Astronomical Telegrams
IAUC 6620: GRB 970228; C/1995 O1
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Circular No. 6620
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)
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GRB 970228
J. L. Tonry, E. M. Hu, and L. L. Cowie, Institute for
Astronomy, University of Hawaii; and R. G. McMahon, Institute of
Astronomy, Cambridge, report: "Spectra (range 375-930 nm;
resolution 1.0 nm FWHM) of the optical transient (IAUC 6584)
associated with GRB 970228 (IAUC 6572) were obtained on the Keck II
10-m telescope (+ LRIS) in six exposures on Mar. 31.25 (500 and
1000 s), Apr. 1.25 (1000 and 1000 s), and Apr. 2.25 UT (1000 and
1000 s) totaling 5500 s under photometric conditions and about
0".8-FWHM seeing. The slit (1" x 2'.9 at p.a. 86.4 deg) was
centered on a nearby star (cf. IAUC 6588) 2".9 east of the
transient. The transient (R.A. = 5h01m46s.65, Decl. = +11o46'53".6,
equinox 2000.0; estimated from the HST WFPC2 image, IAUC 6606) is
weakly detected in the spectrogram with no 'obvious' emission lines.
The nearby star, at position end figures 46s.46, 53".6, has a mid-K-
type spectrum and no evidence for the TiO bands reported on IAUC
6588. A faint emission-line galaxy with redshift 0.638 +/- 0.005
is detected 7".3 east of the transient (position end figures 47s.15,
54".5). A second emission-line galaxy (position end figures 42s.28,
50".7) has a redshift of 0.393 +/- 0.005. The data are available
at http://www.ifa.hawaii/faculty/hu/grb.html or by anonymous ftp to
hubble.ifa.hawaii.edu:/pub/grb970228."
COMET C/1995 O1 (HALE-BOPP)
L. Jorda, Max-Planck-Institut fur Aeronomie, Lindau; F. Colas,
Bureau des Longitudes; J. Lecacheux, Observatoire de Paris, Meudon;
E. Frappa, Planetarium de St.-Etienne; A. Klotz, CESR, Toulouse;
and S. Champenois, Laboratoire d'Astronomie de Lille, report: "The
apparent rotation of the nucleus was clockwise on images obtained
before Feb. 1997 (Kidger et al. 1996, Ap.J. 461, L119) and became
distinctly anticlockwise during March, showing that the north pole
is now directed toward the earth. The spiral jets appeared
straight on visible and infrared images taken at Pic du Midi
Observatory on Mar. 1 +/- 2 days, showing that the line of sight
crossed the equatorial plane of the nucleus at that date. This
implies that the source of the bright jet observed since January is
located in the northern hemisphere, contrary to what we announced
in a preliminary analysis (IAUC 6560). This jet, observed in the
hemisphere directed toward the sun, now has the appearance of
concentric arcs with increasing curvature. A secondary dust jet is
observed at p.a. 195-245 deg."
(C) Copyright 1997 CBAT
1997 April 9 (6620) Daniel W. E. Green
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