[vsnet-grb-info 12901] GRB 130215A: PTF P48 optical detection

[GCN Circulars]

TITLE:   GCN CIRCULAR
NUMBER:  14244
SUBJECT: GRB 130215A: PTF P48 optical detection
DATE:    13/02/21 06:08:29 GMT
FROM:    Leo Singer at CIT/PTF  <lsinger at caltech.edu>

L. P. Singer (Caltech), S. B. Cenko (UC Berkeley), and D. A. Brown
(Syracuse) report on behalf of a larger collaboration:

We have imaged the 3-sigma Swift BAT error circle (S. Barthelmy, GCN
14214) of GRB130215A (Swift548760, S. Barthelmy, GCN 14204) with the
Palomar 48 inch Oschin telescope (P48) as part of the Palomar
Transient Factory (PTF).

Images were obtained in the Mould R filter on 2013-02-15 at 02:35:05
and 04:05:52 UTC, 1.1 and 2.6 hours after the trigger. We detect a
fading point source that is absent in the USNO B-1 catalog at
magnitudes of 16.38 and 17.59 at
    RA(J2000)  =   2h 54m 00.73s
    DEC(J2000) = +13d 23' 43.0"
, matching the ROTSE-IIIb position (GCN 14205, Zheng & Flewelling).

Assuming a power-law decay, these two P48 observations give us an index
alpha=-1.25, consistent with the index of alpha=-1.24 reported by ROTSE
analysis (GCN 14208, Zheng et al.).