NOTE: uvot_fluxes_wget.pl vrs. 2020-11-03a fem at 220420d15h30m42s994373usUT
NOTE: Source region spec. is: 224.329 -17.514 3"
NOTE: Used archived BAT position of 224.32900 -17.51400
NOTE: position reference is GCN_FOM_Notice
WARNING: t_start for light curve (114077) and t_start from the exposure report (0) do not agree.
  Replace ??? in draft Circular with correct value.

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

GRB 220418B: 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 220418B
***???*** s after the Fermi-GUANO trigger (***Author*** et al., GCN Circ. ????).
No optical afterglow consistent with the Fermi-GUANO 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

u_FC            114077       114301          220         >19.7
u               114077       148850         4808         >21.4

The magnitudes in the table are not corrected for the Galactic extinction
due to the reddening of E(B-V) = 0.099 in the direction of the burst
(Schlegel et al. 1998).