GCN Circular 12298
Subject
GRB 110820A: Swift/UVOT Upper Limits
Event
Date
2011-08-22T14:20:06Z (15 years ago)
From
Stefan Immler at NASA/GSFC <stefan.m.immler@nasa.gov>
S. Immler (NASA/CRESST/GSFC) and E. Troja (NASA/GSFC/ORAU)
report on behalf of the Swift/UVOT team:
The Swift/UVOT began settled observations of the field of GRB 110820A
139 s after the BAT trigger (Troja et al., GCN Circ. 12288).
No optical afterglow consistent with the enhanced XRT position
(Beardmore et al., GCN Circ. 12291) and the position of the
optical afterglow candidate Myungshin et al., GCN Circ. 12297)
is detected in the initial UVOT exposures.
Preliminary 3-sigma upper limits using the UVOT photometric system
(Poole et al. 2008, MNRAS, 383, 627) for the first finding chart (FC)
exposure and subsequent exposures are:
Filter T_start(s) T_stop(s) Exp(s) Mag
u_FC 139 389 246 >20.6
v 445 24186 1395 >21.1
b 394 12987 932 >22.0
u 139 18761 2181 >21.8
w1 494 18331 2155 >21.8
m2 469 24536 1716 >20.6
w2 420 23272 1396 >21.2
The magnitudes in the table are not corrected for the Galactic extinction
due to the reddening of E(B-V) = 0.55 in the direction of the burst
(Schlegel et al. 1998).