GCN Circular 14287
Subject
GRB 130306A: Swift Detection of a Possible Afterglow
Event
Date
2013-03-11T15:07:32Z (13 years ago)
From
Mike Siegel at PSU/Swift MOC <siegel@swift.psu.edu>
GRB 130306A: Swift Detection of a Possible Afterglow
M. H. Siegel (PSU), David N. Burrows (PSU) and Dirk Grupe (PSU)
report on behalf of the Swift team:
On 8 March 2013 the Swift spacecraft performed a delayed observation of the
BAT-detected burst GRB 130306A (Siegel et al., GCN 14266), which was also
detected by Fermi GBM (Pelassa, GCN 14270) and Konus/Wind (Golenetskii et al.,
GCN 14275).
We have analyzed 5.1 ks of XRT data, from 146 to 163 ks after the Swift/BAT
trigger. The data are entirely in photon counting (PC) mode.
An X-ray source is detected within the Swift/BAT error circle. The XRT
position is RA, Dec = 279.46147, -11.68123 which is equivalent to:
RA (J2000) = 18 37 50.75
Dec(J2000) = -11 40 52.4
with an uncertainty of 4.0 arcsec (radius, 90% confidence). We do not detect
any fading over the time span of the Swift observations.
The Swift/UVOT began settled observations of the field of GRB 130306A 146
ks after the Swift/BAT trigger. No optical afterglow consistent with the XRT position
is detected in the initial UVOT exposures. Preliminary 3-sigma upper limit using the
UVOT photometric system (Breeveld et al. 2011, AIP Conf. Proc. 1358, 373) for the
initial exposures are:
Filter T_start(s) T_stop(s) Exp(s) Mag
uvw1 145609 162770 4707 >22.2
The magnitudes in the table are not corrected for the Galactic
extinction due to the reddening of E(B-V) = 0.15 in the direction of the
burst (Schlegel et al. 1998).
Further observations are planned to determine if the source is fading.