GCN Circular 14456
Subject
GRB 130427A: Continued P60 follow-up of an extremely bright optical afterglow
Date
2013-04-27T11:52:44Z (11 years ago)
From
S. Bradley Cenko at Caltech <cenko@srl.caltech.edu>
D. A. Perley (Caltech) and S. B. Cenko (UC Berkeley) report:
We have continued observations of the afterglow of GRB130427A (Maselli et
al., GCN 14448) with the Palomar 60-inch telescope until the field set.
Relative to SDSS reference stars in the field, in some select recent
images we estimate afterglow magnitudes of:
r' = 14.86 mag (t = 1.40 hours)
r' = 15.32 mag (t = 2.31 hours)
r' = 15.55 mag (t = 3.10 hours)
This is brighter (by about 1 mag) than any other Swift burst as measured
at similar epoch (as of 2010; Kann et al. ApJ 720:1513), though still
significantly fainter than GRB 030329 which reached approximately 13 mag
at 0.1 day. The rate of fading corresponds to a relatively shallow decay
index of approximately alpha~-0.85, suggesting that this afterglow will
remain bright for an extended period. Worldwide small-telescope follow-up
(including by amateurs) is strongly encouraged.