TITLE:   GCN CIRCULAR
NUMBER:  42193
SUBJECT: GRB 251007B: Swift/UVOT Upper Limits
DATE:    25/10/10 18:00:23 GMT
FROM:    Mike Siegel at PSU/Swift MOC <mhs18@psu.edu>

GRB 251007B: Swift/UVOT Upper Limits

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

The Swift/UVOT began settled observations of the field of GRB 251007B 152 s after the BAT trigger (Melandri et al., GCN Circ. 42147). No optical afterglow consistent with the XRT position (Osborne et al., GCN Circ 42159) 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           152          302          147         >19.8
u_FC               311          561          246         >19.1
white              152         5220          220         >19.9
v                  641         4360          220         >19.2
b                  567         5181          236         >20.3
u                  311         4975          462         >19.5
w1                 691         4770          216         >19.8
m2                 665         4565          216         >19.5
w2                 616          810           39         >18.2

The magnitudes in the table are not corrected for the Galactic extinction
due to the reddening of E(B-V) = 0.786 in the direction of the burst
(Schlegel et al. 1998).