TITLE:   GCN CIRCULAR
NUMBER:  33078
SUBJECT: GRB 221216A: Swift/UVOT Upper Limits
DATE:    22/12/17 16:50:13 GMT
FROM:    Paul Kuin at MSSL  <npkuin@gmail.com>

Paul Kuin (MSSL/UCL) and Simone Dichiara(PSU) report on behalf
of the Swift/UVOT team:

The Swift/UVOT began settled observations of the field of GRB 221116A
113 s after the BAT trigger (Dichiara et al., GCN Circ. 33067).
No optical afterglow consistent with the enhanced XRT position 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              113          263          147         >20.3
white             4797         4997          197         >20.4
u                  325          358           32         >18.3
b                 4592         6041          197         >19.7
uvw1              5618         5818          197         >19.4
uvm2              5413         5613          197         >19.4
uvw2              5003         5203          197         >19.6

The magnitudes in the table are not corrected for the Galactic extinction
due to the reddening of E(B-V) = 0.042 in the direction of the burst
(Schlegel et al. 1998).