GCN Circular 15920
Subject
GRB 140304A: Swift/UVOT Upper Limits
Event
Date
2014-03-04T21:39:55Z (12 years ago)
From
Frank Marshall at GSFC <femarsha@khamseen.gsfc.nasa.gov>
F. E. Marshall (NASA/GSFC) and P. A. Evans (U. Leicester)
report on behalf of the Swift/UVOT team:
The Swift/UVOT began settled observations of the field of GRB 140304A
138 s after the BAT trigger (Evans et al., GCN Circ. 15915).
No optical afterglow consistent with the optical position
(Gorbovskoy et al. GCN Circ. 15914)
is detected in the initial UVOT exposures.
Preliminary 3-sigma upper limits using the UVOT photometric system
(Breeveld et al. 2011, AIP Conf. Proc. 1358, 373) for the first
finding chart (FC) exposure and subsequent exposures are:
Filter T_start(s) T_stop(s) Exp(s) Mag
u_FC 138 388 246 >20.4
v 420 1561 165 >19.5
u 138 1519 529 >20.9
w1 469 1495 156 >19.7
m2 570 1470 117 >20.1
w2 396 1546 156 >20.0
The magnitudes in the table are not corrected for the Galactic extinction
due to the reddening of E(B-V) = 0.08 in the direction of the burst
(Schlegel et al. 1998).
In view of the bright (16.5 mag) afterglow reported by
Gorbovskoy et al., it is likely that the GRB has large
intrinsic extinction or is at a redshift greater than
about 3.5.