GCN Circular 22992
Subject
GRB 180720C: Swift/UVOT Upper Limits
Date
2018-07-21T08:35:26Z (6 years ago)
From
Samantha Oates at MSSL <sro@mssl.ucl.ac.uk>
S. R. Oates (U. Warwick) and S. J. LaPorte (PSU) report on behalf
of the Swift/UVOT team:
The Swift/UVOT began settled observations of the field of GRB 180720C
100 s after the BAT trigger (LaPorte et al., GCN Circ. 22982).
No optical afterglow consistent with the XRT position (Evans et al., GCN
Circ. 22987) 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) 100 250 147 >20.3
white 100 5490 541 >21.0
u (FC) 312 425 111 >19.2
u 312 11199 1193 >20.6
v 4263 5901 393 >19.1
b 3646 11902 1072 >20.8
uvw1 4674 10285 1133 >20.3
uvm2 4469 6106 393 >19.7
uvw2 4058 5696 393 >19.8
The magnitudes in the table are not corrected for the Galactic extinction
due to the significant reddening of E(B-V) = 2.11 in the direction of the burst
(Schlegel et al. 1998).