GCN Circular 7233
Subject
GRB 080129: Gemini-South photometry
Event
Date
2008-01-29T11:48:14Z (18 years ago)
From
Daniel Perley at U.C. Berkeley <dperley@astro.berkeley.edu>
D. A. Perley and J. S. Bloom (UC Berkeley) report on behalf of the
GRAASP collaboration:
Preliminary photometry of our first series of r-band observations of the
candidate afterglow of GRB 080129 (Immler et al., GCN 7226; Bloom, 7229)
yields the following magnitudes, calibrated using three DSS stars*:
t=44 min: R = 22.93 +/- 0.06
t=50 min: R = 22.86 +/- 0.05
t=56 min: R = 22.78 +/- 0.04
t=62 min: R = 22.56 +/- 0.04
t=68 min: R = 22.87 +/- 0.05
As these magnitudes are approximately consistent with the value reported
by Kruehler et al. (GCN 7231/7232) we do not confirm general fading
behavior of this source over the interval of our observations.
However, we note that the fourth exposure shows statistically
significant evidence of a short-lived rebrightening. While an
instrumental cause has not been ruled out, given the location in the
Galactic plane of the source and the very slow fading reported by
Kruehler et al. (0.5 mag from 4 to ~94 minutes, atypical of extragalactic
GRBs), it is possible that the GRB may be an analog of GRB 070610 /
SWIFT J195509.6+261406 (Pagani et al., GCN 6489; Kasliwal et al. 2007,
arXiv:0708.0226), which showed extensive short-time scale early-time
variability above a nearly-constant baseline. Further observations
(including rapid-time-series optical observations), and further analysis
of the X-ray afterglow, are encouraged to further investigate the nature
of this source.
---
*Calibration stars are:
ra dec R2
07:01:10.5033 -07:50:24.020 17.130
07:01:07.7333 -07:51:24.620 17.040
07:01:04.7193 -07:50:46.690 17.310
[GCN OPS NOTE(29jan08): Per author's request, the "Greiner" citation was changed
to "Kruehler".]