GCN Circular 27769

M. H. Siegel (PSU) and B. Sbarufatti (PSU)
report on behalf of the Swift/UVOT team:

The Swift/UVOT began settled observations of the field of GRB 200519A
58 s after the BAT trigger (Sbarufatti et al., GCN Circ. 27756
Not found
 
 
).
A source consistent with the XRT position
(Sbarufatti et al. GCN Circ. 27756
Not found
 
 
)
is detected in the initial UVOT exposures.

The preliminary UVOT position is:
  RA  (J2000) =  17:01:20.01 = 255.33337 (deg.)
  Dec (J2000) = -30:22:41.1  = -30.37808 (deg.)
with an estimated uncertainty of 0.42 arc sec. (radius, 90% confidence).

Preliminary detections and 3-sigma upper limits using the UVOT photometric system
(Breeveld et al. 2011, AIP Conf. Proc. 1358, 373) for the early exposures are: 

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

white               58          208          147         15.43 +/- 0.02
v                  599          619           20         16.30 +/- 0.16
b                  525          545           19         17.13 +/- 0.13
u                  270          519          246         16.27 +/- 0.04
w1                 648          840           39         17.46 +/- 0.25
w2                 747          766           19        >17.5

The magnitudes in the table are not corrected for the Galactic extinction
due to the reddening of E(B-V) = 0.47 in the direction of the burst
(Schlegel et al. 1998).