GCN Circular 7680
Subject
GRB 080503: No further optical rebrightening
Date
2008-05-05T13:15:41Z (16 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 a larger
collaboration:
Starting at UT 11:32 on the night of 2008-05-05, we began a series of
additional r-band imaging follow-up observations of the optical
counterpart associated with GRB 080503 (GCN 7665, Mao et al.), using
Gemini-North (+GMOS).
The new source (s2) reported in our previous circular (GCN 7678) is
still present at about the same magnitude. Using a stack of 9x180s
images, we present the following measurement of the magnitudes of s1 and s2:
s1: R = 26.33 +/- 0.20
s2: R = 25.46 +/- 0.09
This is consistent (within about 2-sigma) with the previous night's
measurement and suggests neither additional rebrightening nor dramatic
fading. We continue to strongly encourage follow-up with large-aperture
instruments.
We also issue the following correction to GCN 7678: the data table at
the bottom (with heading "UT_start exposure filter magnitude") is not
valid. This is photometry of s1 based on an older calibration, and
including a Keck R-band limiting magnitude that will be refined in a
future circular. The preceding photometry of s1 and s2 in that circular
is still valid.
To reiterate, the r-band evolution of the optical counterpart (s2) to
date, calibrated to USNO B1.0 R-band, is given by:
t(hr) magnitude
0.98 R > 25.6
1.5 R > 26.5
26.0 R = 25.28 +/- 0.09
47.4 R = 25.46 +/- 0.09
Further observations are ongoing.