GCN Circular 21649
Subject
GRB 170822A: Swift/UVOT Upper Limits
Event
Date
2017-08-22T18:07:41Z (8 years ago)
From
Sam Emery at MSSL-UCL <samuel.emery.15@ucl.ac.uk>
S.W.K. Emery (UCL-MSSL) and A. Melandri (INAF-OAB)
report on behalf of the Swift/UVOT team:
The Swift/UVOT began settled observations of the field of GRB 170822A
171 s after the BAT trigger (Melandri et al., GCN Circ. 21640).
No optical afterglow consistent with the XRT position
(Beardmore et al., GCN Circ. 21643)
and the optical position
(Tello et al., GCN Circ. 21642)
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
white_FC 171 321 148 >20.4
white 529 1894 284 >21.3
v 406 1936 165 >19.2
b 504 1870 156 >20.2
u 480 1845 156 >19.8
uvw1 455 1820 155 >19.7
uvm2 604 1101 39 >18.1
uvw2 381 1921 175 >19.9
The magnitudes in the table are not corrected for the Galactic extinction
due to the reddening of E(B-V) = 0.17 in the direction of the burst
(Schlegel et al. 1998).