GCN Circular 9997
Subject
GRB 091003: Lick observations and possible SDSS host galaxy
Date
2009-10-06T22:17:22Z (15 years ago)
From
Daniel Perley at U.C. Berkeley <dperley@astro.berkeley.edu>
D. A. Perley, J. Choi, A. J. L. Morton, and M. Ganeshalingam (UC
Berkeley) report:
We observed the position of Fermi GRB 091003 (Rau et al., GCN9983) using
the Nickel 1m telescope at Lick Observatory on the night of 2009-10-06
(UT) starting at 04:06 for a series of five 600-second exposures in
R-band. The afterglow (Starling and Beardmore, GCN 9986; Gronwall and
Starling, GCN 9987) is marginally detected in the combined frame.
Calibrating to nearby SDSS stars transformed to R-band using the
equations of Lupton et al. (2005) we estimate a magnitude of
R = 21.2 +/- 0.4 (t_mid = 3.00 days)
This suggests only limited fading since the observations of Wiersama et
al. (GCN 9995).
Further, we note that a source coincident with this position is detected
in the SDSS survey imaging. The object (SDSS J164604.70+363731.1) has a
magnitude of r = 23.2 and is classified as a star, but could represent
the host galaxy of this event. A low redshift would also be consistent
with the absence of absorption signatures in the spectrum of Wiersema et
al. and with the Swift UVW2 detection (Pritchard et al., GCN 9990). We
encourage further observations, in particular additional spectroscopy,
of this object.