=========== Draft Upper Limit Circular ========

GRB 160623A: Swift/UVOT Upper Limits

***UBS*** (***INSTITUTION***) and ***BA*** (***BA INSTITUTION***)
report on behalf of the Swift/UVOT team:

The Swift/UVOT began settled observations of the field of GRB 160623A
40254 s after the LAT trigger (***Author*** et al., GCN Circ. ????).
No optical afterglow consistent with the XRT position
(Mingo et al. GCN Circ. 19558)
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 initial exposures are:

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

v                40657        51652         2859         >21.8
u                40254        51253         2008         >21.8

The magnitudes in the table are not corrected for the Galactic extinction
due to the reddening of E(B-V) = 1.35 in the direction of the burst
(Schlegel et al. 1998).