GCN Circular 27532

N. P. M. Kuin (UCL-MSSL) and K. K. Simpson (PSU) report on behalf of the
Swift/UVOT team:

The Swift/UVOT began settled observations of the field of GRB 200410A
104 s after the BAT trigger (Simpson et al., GCN Circ. 27518
Not found
 
 
).
A source consistent with the XRT position (Goad et al. GCN Circ. 27522
Not found
 
 
)
is detected in the initial UVOT exposures.

The uvot position has been determined from the first white image to be
RA  = 19:58:35.3
Dec = +51:46:53.0
or 299.64717 =51.78138 Deg (J2000) with an error estimate of 0.5".
There are two nearby stars visible at 4 and 6 arcsec.


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              104          254          147         19.51 +/- 0.14
v                 5051         6869          396         21.23 +/- 0.90
b                  572         1519           98         19.61 +/- 0.32
u                  317          567          246         20.39 +/- 0.37
w1                 696         1294           57        >19.8
m2                 671         1220           57        >20.0
w2                 622         1270           57        >19.9

The magnitudes in the table are not corrected for the Galactic extinction
due to the reddening of E(B-V) = 0.15 in the direction of the burst
(Schlegel et al. 1998).