NOTE: uvot_fluxes_wget.pl vrs. 2020-11-03a fem at 210622d02h46m35s676499usUT
NOTE: Source region spec. is: 238.78646 -54.06136 4"
NOTE: Used archived XRT position of 238.78646 -54.06136  4.00
NOTE: position reference is GRB_Auto_Processing

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

GRB 210621: 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 210621
45 s after the BAT trigger (***Author*** et al., GCN Circ. ????).
No optical afterglow consistent with the XRT position
*** POSITION REFERENCE is GRB_Auto_Processing ***
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            45          195          147         >20.5
u_FC               258          507          246         >20.1
white               45         1358          373         >21.0
v                  587         1408           97         >19.5
b                  513         1506           97         >19.7
u                  258         1481          343         >20.2
w1                 637         1457           97         >19.8
m2                 612         1432           97         >20.0
w2                 563         1383           97         >19.2

The magnitudes in the table are not corrected for the Galactic extinction
due to the reddening of E(B-V) = 21.992 in the direction of the burst
(Schlegel et al. 1998).