NOTE: uvot_fluxes_wget.pl vrs. 2023-03-23 fem at 230905d12h20m22s995733usUT
NOTE: Source region spec. is: 9.91171 -40.94931 4"
NOTE: Used archived XRT position of   9.91171 -40.94931  4.00
NOTE: position reference is GCN_Circulars-34610

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

GRB 230903A: Swift/UVOT Upper Limits

***UBS*** (***INSTITUTION***) and A. D'Ai (INAF-IASFPA)
report on behalf of the Swift/UVOT team:

The Swift/UVOT began settled observations of the field of GRB 230903A
114 s after the BAT trigger (D'Ai et al., GCN Circ. 34610).
No optical afterglow consistent with the XRT position
*** POSITION REFERENCE is GCN_Circulars-34610 ***
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           114          264          147         >21.1
u_FC               272          522          246         >20.7
white              114          962          234         >21.0
u                  272          522          246         >20.7

The magnitudes in the table are not corrected for the Galactic extinction
due to the reddening of E(B-V) = 0.012 in the direction of the burst
(Schlegel et al. 1998).