NOTE: uvot_fluxes_wget.pl vrs. 2024-08-27 fem at 251222d06h36m46s261617usUT
NOTE: Source region spec. is: 101.42771 0.73217 4"
NOTE: Used archived XRT position of 101.42771   0.73217  4.00
NOTE: position reference is GCN_Circulars-43175

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

GRB 251221A: Swift/UVOT Upper Limits

***UBS*** (***INSTITUTION***) and Ambrosi (INAF-IASFPA)
report on behalf of the Swift/UVOT team:

The Swift/UVOT began settled observations of the field of GRB 251221A
143 s after the BAT trigger (Ambrosi et al., GCN Circ. 43166).
No optical afterglow consistent with the XRT position
*** POSITION REFERENCE is GCN_Circulars-43175 ***
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           143          292          147         >20.5
u_FC               301          550          246         >19.7
white              143         1546          392         >21.2
v                  631         1597          117         >19.7
b                  557         5245          108         >19.9
u                  301         5229          520         >20.4
w1                 680         1647          117         >19.8
m2                 655         1621          117         >19.5
w2                 606         1572          117         >19.6

The magnitudes in the table are not corrected for the Galactic extinction
due to the reddening of E(B-V) = 1.088 in the direction of the burst
(Schlegel et al. 1998).