GCN Circular 23460

A. A. Breeveld (UCL-MSSL) and E. Sonbas (Adiyaman Univ.)
report on behalf of the Swift/UVOT team:

The Swift/UVOT began settled observations of the field of GRB 181126A
80s after the BAT trigger (Sonbas et al., GCN Circ. 23453
Not found
 
 
).
No optical afterglow consistent with the XRT position (Beardmore et al.,
GCN Circ. 23455
Not found
 
 
) 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            80          230          147         >20.4
white               80         1181          342         >20.5
v                  622         1069           58         >18.0
b                 1147         1167           20         >18.2
u                  292         1142          285         >20.1
w1                 671         1118           58         >20.2
m2                 646         1093           58         >19.0
w2                 597         1044           58         >18.4

The magnitudes in the table are not corrected for the Galactic
extinction due to the reddening of E(B-V) = 0.07 in the direction of the
burst (Schlegel et al. 1998).