GCN Circular 29303

M. H. Siegel (PSU) and Ambrosi (INAF-IASFPA)
report on behalf of the Swift/UVOT team:

The Swift/UVOT began settled observations of the field of GRB 210112A
83 s after the BAT trigger (Ambrosi et al., GCN Circ. 29289
Not found
 
 
).
A source consistent with the XRT position
(Goad et al. GCN Circ. 29290
Not found
 
 
)
is detected in the initial UVOT exposures.

The preliminary UVOT position is:
  RA  (J2000) =  14:36:01.49 = 219.00619 (deg.)
  Dec (J2000) = +33:03:15.3  =  33.05424 (deg.)
with an estimated uncertainty of 0.50 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               83          233          147         19.54 +/- 0.10
v                  626         1419           97        >18.5
b                  551         1517           97        >19.1
u                  296         1493          304        >20.2
w1                 675         1468           78        >19.1

The magnitudes in the table are not corrected for the Galactic extinction
due to the reddening of E(B-V) = 0.014 in the direction of the burst
(Schlegel et al. 1998).