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

GRB 150204A: Swift/UVOT Upper Limits

A. A. Breeveld (UCL-MSSL) and D. Malesani (***BA INSTITUTION***)
report on behalf of the Swift/UVOT team:

The Swift/UVOT began settled observations of the field of GRB 150204A
51182 s after the BAT trigger (***Author*** et al., GCN Circ. ????).
No optical afterglow consistent with the XRT position
(Melandri et al. GCN Circ. 17409)
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                57368        58276          885         >21.3
u                52088        52670          568         >19.5
w1               51182        63642         1495         >20.9
m2               58281        63016         1027         >20.4
w2               56461        57361          886         >20.7

The magnitudes in the table are not corrected for the Galactic extinction
due to the reddening of E(B-V) = 0.821 in the direction of the burst
(Schlegel et al. 1998).