NOTE: uvot_fluxes_wget.pl vrs. 2018-01-16 fem at 180426d17h10m51s587783usUT
NOTE: Source region spec. is: 57.459 -48.782 3"
NOTE: Used archived BAT position of  57.45900 -48.78200
NOTE: position reference is GCN_Position_Notice

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

GRB 180426: Swift/UVOT Upper Limits

A. A. Breeveld (UCL-MSSL) and ***BA*** (***BA INSTITUTION***)
report on behalf of the Swift/UVOT team:

The Swift/UVOT began settled observations of the field of GRB 180426
3425 s after the BAT trigger (***Author*** et al., GCN Circ. ????).
No optical afterglow consistent with the BAT position
*** POSITION REFERENCE is GCN_Position_Notice ***
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          3425         3575          147         >20.1
white             3425         3575          147         >20.1
v                 3582         3628           45         >17.8

The magnitudes in the table are not corrected for the Galactic extinction
due to the reddening of E(B-V) = 0.01 in the direction of the burst
(Schlegel et al. 1998).