TITLE:   GCN CIRCULAR
NUMBER:  22717
SUBJECT: GRB 180512A: Swift/UVOT Upper Limits
DATE:    18/05/13 10:53:43 GMT
FROM:    Paul Kuin at MSSL  <npkuin@gmail.com>

N. P. M. Kuin (UCL-MSSL) and Deich (PSU)
report on behalf of the Swift/UVOT team:

The Swift/UVOT began settled observations of the field of GRB 180512A
218 s after the BAT trigger (Deich et al., GCN Circ. 22710).  No optical
afterglow consistent with the XRT position (Evans et al. GCN Circ. 22715)
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           218          368          147         >21.1
white              218         4358          344         >21.2
v                 5986         6120          132         >19.0
b                 3953         4153          197         >20.7
u                 3748        16254          422         >20.7
w1                3543        16019         1107         >20.3
m2                9380        10280          886         >20.9
w2                5781         5981          197         >20.1

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).