TITLE:   GCN CIRCULAR
NUMBER:  27308
SUBJECT: GRB 200303A: Swift/UVOT Upper Limits
DATE:    20/03/03 15:21:17 GMT
FROM:    Alice Breeveld at MSSL-UCL  <a.breeveld@ucl.ac.uk>

A. A. Breeveld (UCL-MSSL) and S. B. Cenko (GSFC) report on behalf of the Swift/UVOT team:

The Swift/UVOT began settled observations of the field of
GRB 200303A 96 s after the BAT trigger (Cenko et al., GCN Circ. 27297).
No optical afterglow consistent with the XRT position
(Goad et al. GCN Circ. 27300) 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            96          246          147         >20.7
u_FC               308          558          246         >20.4
white               96         5034          550         >21.5
v                 1219         1238           19         >18.4
b                 1144         1163           19         >19.4
u                  308          558          246         >20.4

The magnitudes in the table are not corrected for the Galactic extinction
due to the reddening of E(B-V) = 0.02 in the direction of the burst
(Schlegel et al. 1998).