NOTE: uvot_fluxes_wget.pl vrs. 2020-11-03a fem at 220921d22h51m52s424652usUT
NOTE: Source region spec. is: 66.790 -40.250 3"
NOTE: Used archived BAT position of  66.79000 -40.25000
NOTE: position reference is GCN_Notice

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

GRB 220921: Swift/UVOT Upper Limits

***UBS*** (***INSTITUTION***) and ***BA*** (***BA INSTITUTION***)
report on behalf of the Swift/UVOT team:

The Swift/UVOT began settled observations of the field of GRB 220921
27599 s after the LAT trigger (***Author*** et al., GCN Circ. ????).
No optical afterglow consistent with the LAT position
*** POSITION REFERENCE is GCN_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 initial exposures are:

Filter         T_start(s)   T_stop(s)      Exp(s)         Mag

w2               27599        28311          701         >20.6

The magnitudes in the table are not corrected for the Galactic extinction
due to the reddening of E(B-V) = 0.049 in the direction of the burst
(Schlegel et al. 1998).