TITLE:   GCN CIRCULAR
NUMBER:  31483
SUBJECT: GRB 220117B: Swift/UVOT Upper Limits
DATE:    22/01/18 14:15:21 GMT
FROM:    Alice Breeveld at MSSL-UCL  <a.breeveld@ucl.ac.uk>

A. A. Breeveld (UCL-MSSL) and A. Melandri (INAF-OAB) report on behalf of the Swift/UVOT team:

The Swift/UVOT began settled observations of the field of GRB 220117B 104 s after the BAT trigger 
(Melandri et al., GCN Circ. 31468).
No optical afterglow consistent with the XRT position (Evans et al. GCN Circ. 31473) 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           104          254          147         >19.7
white              104         3930          344         >20.5
v                 4141         4341          197         >19.2
b                 3525         5048          281         >20.7
u                  262         4957          239         >19.8
w1                4552         4752          197         >20.0
m2                4346         4546          197         >20.3
w2                3936         4136          197         >20.4

The magnitudes in the table are not corrected for the Galactic extinction due to the reddening of 
E(B-V) = 0.075 in the direction of the burst (Schlegel et al. 1998).