TITLE:   GCN CIRCULAR
NUMBER:  19372
SUBJECT: GRB 160501A: Swift/UVOT Upper Limits
DATE:    16/05/01 20:00:06 GMT
FROM:    Alice Breeveld at MSSL-UCL  <a.breeveld@ucl.ac.uk>

A. A. Breeveld (UCL-MSSL) and J. R. Cummings (NASA/UMBC)
report on behalf of the Swift/UVOT team:

The Swift/UVOT began settled observations of the field of GRB 160501A
136s after the BAT trigger (Cummings et al., GCN Circ. 19365).
No optical afterglow consistent with the XRT position (Evans et al. GCN 
Circ. 19369) 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           136          286          147         >20.3
u_FC               295          544          246         >19.7
white              575         1543          245         >21.1
v                  625         1594          117         >18.9
b                  551         1518           97         >19.9
w1                 674         1643          117         >19.2
m2                 649         1618          117         >19.7
w2                 600         1569          117         >19.2

The magnitudes in the table are not corrected for the Galactic 
extinction due to the reddening of E(B-V) = 0.18 in the direction of the 
burst (Schlegel et al. 1998).