GCN Circular 11969

A. A. Breeveld (MSSL-UCL) and V. Mangano (INAF-IASFPA)
report on behalf of the Swift/UVOT team:

The Swift/UVOT began settled observations of the field of GRB 110422A
822 s after the BAT trigger (Mangano et al., GCN Circ. 11957
Not found
 
 
).
An optical afterglow consistent with the optical position found by 
Klunko et al. (GCN 11958
Not found
 
 
) and others is found in the UVOT, and is 
clearly fading. It is detected in initial exposures in both white and 
b, and also in v and u when the initial exposures are summed up.
Preliminary magnitudes and 3-sigma upper limits using the UVOT 
photometric system (Poole et al. 2008, MNRAS, 383, 627) for the first 
finding chart (FC) exposure and subsequent exposures are:

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

white_FC           822          972          147         18.80 �� 0.12
white (summed)    1054         1766          97.2        19.5 �� 0.23
white             7837         8037          197          >20.4
v (summed)        1104         2336          156         18.72 �� 0.35
b                 1029         1049          19.4        18.02 �� 0.3
b (summed)        1202         2435          156         18.97 �� 0.22
u (summed)        1004         2410          175         18.8 �� 0.26
w1 (summed)        980         2385          175         >19.4
m2 (summed)       1128         2360          156         >19.4
w2 (summed)       1079         2310          156         >19.6

The values quoted above 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).

[GCN OPS NOTE(23apr11): Per author's request, the spelling on the Klunko
reference was corrected.]