NOTE: uvot_fluxes_wget.pl vrs. 2018-01-16 fem at 180721d00h11m13s857694usUT
NOTE: Source region spec. is: 265.63488 -26.63042 4"
NOTE: Used archived XRT position of 265.63488 -26.63042  4.00
NOTE: position reference is GCN_Circulars-22982
WARNING: Did not find t_start in exposure report.

=========== Draft Upper Limit Circular ========

GRB 180720C: Swift/UVOT Upper Limits

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
(LaPorte et al. GCN Circ. 22982)
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          216          114         >20.0
white              100          216          114         >20.0

The magnitudes in the table are not corrected for the Galactic extinction
due to the reddening of E(B-V) = 2.09 in the direction of the burst
(Schlegel et al. 1998).