GCN Circular 10058
Subject
GRB 091020: Lick observations
Date
2009-10-21T14:24:31Z (15 years ago)
From
Daniel Perley at U.C. Berkeley <dperley@astro.berkeley.edu>
D. A. Perley (UC Berkeley) reports:
I observed the location of GRB 091020 (Racusin et al, GCN 10048)
starting at UT 2009-10-21 12:30 using the Nickel 40-inch telescope at
Lick Observatory. A series of nine exposures in R-band were acquired,
followed by five exposures in I-band and an additional sequence in
R-band during morning twilight. All exposures except for the first were
of 180 seconds duration.
The afterglow is marginally detected in individual frames and
well-detected in a combined stack. Calibrating relative to five nearby
SDSS standard stars transformed to R-band using the transformation
equation of Lupton (2005), the estimated magnitude of the afterglow in
the first R-band stack is:
R = 20.91 +/- 0.13 mag (t_mid = 15.17 hr)
Additional follow-up is planned if weather permits.