NOTE: uvot_fluxes_wget.pl vrs. 2020-11-03a fem at 210504d18h21m56s031174usUT
NOTE: Source region spec. is: 222.3933 -30.5322 4"
NOTE: Used archived XRT position of 222.39330 -30.53220  4.00
NOTE: position reference is GCN_Circ-29929
WARNING: t_start for light curve (196) and t_start from the exposure report (0) do not agree.
  Replace ??? in draft Circular with correct value.

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

GRB 210504A: Swift/UVOT Upper Limits

***UBS*** (***INSTITUTION***) and A. P. Beardmore (U. Leicester)
report on behalf of the Swift/UVOT team:

The Swift/UVOT began settled observations of the field of GRB 210504A
***???*** s after the BAT trigger (Beardmore et al., GCN Circ. 29929).
No optical afterglow consistent with the XRT position
*** POSITION REFERENCE is GCN_Circ-29929 ***
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           218          368          147         >20.7
white              218         1877          450         >21.5
v                  196         1926          188         >19.8
b                  473         1852          156         >19.9
u                  448         1827          156         >20.7
w1                 424         1803          156         >19.8
m2                1242         1778           58         >19.1
w2                 523         1902          117         >20.5

The magnitudes in the table are not corrected for the Galactic extinction
due to the reddening of E(B-V) = 0.138 in the direction of the burst
(Schlegel et al. 1998).