GCN Circular 19593

M. De Pasquale (UCL-MSSL) and A. Maselli (INAF-IASFPA)
report on behalf of the Swift/UVOT team:

The Swift/UVOT began settled observations of the field of GRB 160625A
7183 s after the BAT trigger (Maselli et al., GCN Circ. 19577
Not found
 
 
).
No optical afterglow consistent with the XRT position
(Burrows et al. GCN Circ. 19578
Not found
 
 
) is detected in the UVOT exposures.
We note the presence of a source approximately 3'' from the
XRT position. This source is present in the USNO catalogue.
Preliminary 3-sigma upper limits using the UVOT photometric system
(Breeveld et al. 2011, AIP Conf. Proc. 1358, 373) for the
exposures are:

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

white             7183         7952          344         >20.8
v                 8163         8363          197         >19.0
b                 7548         7747          197         >19.9
u                 7342         7542          197         >19.4
m2                8368         8483          113         >18.9
w2                7958         8158          197         >19.6

The magnitudes in the table are not corrected for the substantial Galactic
extinction due to the reddening of E(B-V) = 1.51 in the direction of the
burst (Schlegel et al. 1998).

-- 

Dr. Massimiliano De Pasquale
Research associate - Swift UVOT scientist
Mullard Space Science Laboratory, University College London