TITLE:   GCN CIRCULAR
NUMBER:  17323
SUBJECT: GRB 150120A: Swift/UVOT Upper Limits
DATE:    15/01/20 19:56:38 GMT
FROM:    Margaret Chester at PSU  <chester@swift.psu.edu>

M. M. Chester (PSU) and V. D'Elia (ASDC) report on behalf of 
the Swift/UVOT team:

The Swift/UVOT began settled observations of the field of GRB 150120A
83 s after the BAT trigger (D'Elia et al., GCN Circ. 17310).
No optical afterglow consistent with the XRT position (Evans et al. 
GCN Circ. 17317) 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) exposures and subsequent exposures are:

Filter         T_start(s)   T_stop(s)      Exp(s)         Mag

white_FC            83          233          147         >20.6
u_FC               295          545          246         >20.1
white               83         5674          461         >21.0
v                  624         6085          432         >19.5
b                  550        10198          449         >21.0
u                  295         6700          658         >20.6
w1                 674         6495          432         >20.5
m2                 649         6290          432         >21.1
w2                 600         5880          432         >20.5

The magnitudes in the table are not corrected for the Galactic extinction
due to the reddening of E(B-V) = 0.10 in the direction of the burst
(Schlegel et al. 1998).