NOTE: uvot_fluxes_wget.pl vrs. 2020-11-03a fem at 210427d14h23m22s801694usUT
NOTE: Source region spec. is: 263.105 +54.060 3"
NOTE: Used archived BAT position of 263.10500  54.06000
NOTE: position reference is GCN_FOM_Notice

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

GRB 210427: 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 210427
1472 s after the BAT trigger (***Author*** et al., GCN Circ. ????).
No optical afterglow consistent with the BAT position
*** POSITION REFERENCE is GCN_FOM_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 first
finding chart (FC) exposure and subsequent exposures are:

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

white_FC          1472         1622          147         >19.9
white             1472         1622          147         >19.9
v                 1629         1648           19         >17.2
b                 5674         5740           65         >19.8
u                 5469         5669          197         >20.1
w1                5264         5464          197         >19.9

The magnitudes in the table are not corrected for the Galactic extinction
due to the reddening of E(B-V) = 0.044 in the direction of the burst
(Schlegel et al. 1998).