TITLE:   GCN CIRCULAR
NUMBER:  27783
SUBJECT: GRB 200522A: Swift/UVOT Upper Limits
DATE:    20/05/22 21:43:20 GMT
FROM:    Paul Kuin at MSSL  <npkuin@gmail.com>

N. P. M. Kuin (UCL-MSSL) and P. A. Evans (U. Leicester)
report on behalf of the Swift/UVOT team:

The Swift/UVOT began settled observations of the field of GRB 200522A
448 s after the BAT trigger (Evans et al., GCN Circ. 27778).
No optical afterglow consistent with the XRT position
(Evans et al. GCN Circ. 27778) 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           448          598          147         >19.5
white              448          598          147         >19.5
v                  605          624           19         >17.2

The magnitudes in the table are not corrected for the Galactic extinction
due to the reddening of E(B-V) = 0.03 in the direction of the burst
(Schlegel et al. 1998).