GCN Circular 14449
Subject
GRB 130427A: P60 early nondetection
Date
2013-04-27T08:39:09Z (12 years ago)
From
Daniel Perley at Caltech <dperley@astro.caltech.edu>
D. A. Perley (Caltech) reports on behalf of a larger collaboration:
The Palomar 60-inch telescope automatically responded to GRB 130427A
(Maselli et al., GCN 14448) and began taking observations at 07:52:22 UT
(4.42 minutes after the BAT trigger). A series of 60-second images were
taken in r, i, and z filters; observations are still ongoing. Inspection
of individual frames shows no detection of an optical transient
consistent with the XRT position to approximately r > 20.6 mag, i > 20.7
mag, z > 19.7 mag.
Nondetection of an afterglow in rapidly-triggered P60 observations is
unusual (Cenko et al. 2009, ApJ 693, 1484), especially in the presence
of an very bright GRB and early XRT afterglow. This is suggestive of a
highly extinguished (or possibly high-redshift) burst, and may indicate
that the possible UVOT source reported by Maselli et al. was spurious.
Further observations, especially in the NIR, are strongly encouraged.