Central Bureau for Astronomical Telegrams
IAUC 6691: 1997ct; GRB 970616
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Circular No. 6691
Central Bureau for Astronomical Telegrams
INTERNATIONAL ASTRONOMICAL UNION
Mailstop 18, Smithsonian Astrophysical Observatory, Cambridge, MA 02138, U.S.A.
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SUPERNOVA 1997ct IN ANONYMOUS GALAXY
S. Jha, P. Garnavich, P. Challis and R. Kirshner, Harvard-
Smithsonian Center for Astrophysics, report that CCD images of SN
1997ct (cf. IAUC 6690) taken by M. Gomez on July 1.2 UT at the
Whipple Observatory 1.2-m telescope yield V = 18.6 and precise
position R.A. = 14h07m26s.88, Decl. = +70o26'05".9 (equinox 2000.0,
uncertainty +/- 0".4), corresponding to an offset of 9".4 east and
1".4 south from the host galaxy's center. A spectrogram taken by
D. Koranyi with the 1.5-m telescope indicates that the supernova is
of type Ia, four to six weeks after maximum. The host galaxy is at
redshift 0.030, based on the observed H-alpha emission.
GRB 970616
M. A. Pahre, J. C. Clemens, S. R. Kulkarni, and I. N. Reid,
Palomar Observatory, California Institute of Technology; D. A.
Frail, National Radio Astronomy Observatory; and J. Cordes, Cornell
University, report: "Photographic IV-N plates acquired by J.
Mueller and D. Mendenhall on the Palomar 1.2-m Oschin telescope
(June 17.5 and 20.5 UT) of the optical transient (OT) identified by
Galama et al. (IAUC 6687) in the field of GRB 970616 show no
evidence for the OT to the plate limit of Cousins I about 18.
Palomar 1.52-m telescope observations of the OT (with a CCD and a
near-infrared camera) yield the following magnitudes: June 20.5, J
= 18.30 +/- 0.05, K = 16.9 +/- 0.4; June 21.5, J = 18.23 +/- 0.11;
June 23.5, Cousins I >/= 21.5 (3-sigma limit, at which it was
marginally detected). Palomar 5-m Hale telescope observations of
the OT on June 28.5 show the source to have J = 18.31 +/- 0.04 and
K = 17.06 +/- 0.17. The source exhibited no detected variability
in either the J or K bands between June 20 and 28, consistent with
the nondetection of variability reported by Castro-Tirado et al.
(IAUC 6688) in the K band. Thus, on June 21 the colors of the OT
were R-J = +4.25 and J-K = +1; on June 28, J-K = +1.25; and,
interpolating the R-band measurements of Galama et al., we derive
R-I about +2 on June 23. These colors, with the single exception
of the R measurement of Galama et al. on June 21, are fully
consistent with those of a late-type star such as LHS 2924. Very
Large Array monitoring observations during the period June 19.5-
25.7 show no source at the position of the OT with upper limits (1
sigma) of 0.05 mJy (at an observed frequency of 8.5 GHz), 0.05 mJy
(at 5 GHz), and 0.1 mJy (at 1.4 GHz)."
(C) Copyright 1997 CBAT
1997 July 1 (6691) Daniel W. E. Green
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