GCN Circular 12752
Subject
GRB 111228A: Swift/UVOT Detection
Date
2011-12-29T04:40:16Z (12 years ago)
From
Paul Kuin at MSSL <npkuin@gmail.com>
N. P. M. Kuin (MSSL-UCL) and Ukwatta (MSU) report on
behalf of the Swift/UVOT team:
The Swift/UVOT began settled observations of the field of
GRB 111228A 155 s after the BAT trigger (Ukwatta et al.,
GCN Circ. 12737). The UVOT position is consistent with
the enhanced XRT position (Goad et al., GCN Circ. 12747)
within the measurement accuracy.
Preliminary detections and 3-sigma upper limits using the UVOT
photometric system (Breeveld et al. 2011, AIP Conf. Proc.
1358, 373) for the early exposures are:
Filter T_start(s) T_stop(s) Exp(s) Mag
white 155 305 147 17.30 +/- 0.03
v 389 759 58 17.73 +/- 0.16
b 488 508 19 17.71 +/- 0.15
u 463 483 19 16.70 +/- 0.12
w1 439 459 19 16.59 +/- 0.17
m2 764 784 19 16.84 +/- 0.24
The preliminary lightcurves show achromatic behavior during the
first 1200s and appears to maintain brightness levels until around
7000s after the trigger, when the decay in brightness sets in.
The magnitudes in the table are not corrected for the Galactic extinction
due to the reddening of E(B-V) = 0.03 in the direction of the burst
(Schlegel et al. 1998).