GCN Circular 22379
Subject
GRB 180204A: Swift/UVOT Upper Limits
Date
2018-02-04T16:50:12Z (6 years ago)
From
Paul Kuin at MSSL <npkuin@gmail.com>
N. P. M. Kuin (UCL-MSSL) and K. L. Page (U. Leicester)
report on behalf of the Swift/UVOT team:
The Swift/UVOT began settled observations of the field of GRB 180204A
92 s after the BAT trigger (Page et al., GCN Circ. 22375). A star is
present in the GSC whos position is consistent with the enhanced XRT
position (Osborne et al. GCN Circ. 22377). No optical afterglow above
the stellar flux has been 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
white_FC 92 242 147 >20.3
u_FC 304 554 246 >19.9
white 92 17884 1210 >20.8
v 633 10587 1107 >19.0
b 560 23622 1840 >20.7
u 304 23062 2409 >21.1
w1 3943 22148 1917 >21.0
m2 658 11492 1095 >20.8
w2 609 6398 413 >20.1
The magnitudes in the table are not corrected for the Galactic extinction
due to the reddening of E(B-V) = 0.10 in the direction of the burst
(Schlegel et al. 1998).