TITLE:   GCN CIRCULAR
NUMBER:  30456
SUBJECT: GRB 210712A: Swift/UVOT Upper Limits
DATE:    21/07/12 23:12:07 GMT
FROM:    Mike Siegel at PSU/Swift MOC  <mhs18@psu.edu>

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 210712A
91 s after the BAT trigger (Sbarufatti et al., GCN Circ. 30447).
No optical afterglow consistent with the enhanced XRT position
(Evans et al. GCN Circ. 30453) 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            91          241          147         >19.5
u_FC               304          554          246         >19.6
white               91          604          167         >19.5
b                  560          579           19         >18.0
u                  304          554          246         >19.6
w2                 609          614            4         >17.5

The magnitudes in the table are not corrected for the Galactic extinction
due to the reddening of E(B-V) = 0.076 in the direction of the burst
(Schlegel et al. 1998).