TITLE:   GCN CIRCULAR
NUMBER:  29403
SUBJECT: GRB 210205A: Swift/UVOT Upper Limits
DATE:    21/02/05 18:16:08 GMT
FROM:    Alexander Belles at PSU/Swift  <aub1461@psu.edu>

A. Belles (PSU) and S. Dichiara (NASA/GSFC/UMCP)
report on behalf of the Swift/UVOT team:

The Swift/UVOT began settled observations of the field of GRB 210205A
139 s after the BAT trigger (Dichiara et al., GCN Circ. 29397).
No optical afterglow consistent with the XRT position
(Osborne et al. GCN Circ. 29399)
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           139          289          147         >20.5
white              139         4057          344         >20.6
v                 4268         4468          197         >19.4
b                 3652         5159          265         >20.1
u                  297         5084          255         >19.7
w1                4678         4878          197         >19.9
m2                4473         4673          197         >20.8
w2                4063         4263          197         >19.3

The magnitudes in the table are not corrected for the Galactic extinction
due to the reddening of E(B-V) = 0.716 in the direction of the burst
(Schlegel et al. 1998).