TITLE:   GCN CIRCULAR
NUMBER:  22709
SUBJECT: GRB 180510A: Swift/UVOT followup observations
DATE:    18/05/12 07:21:32 GMT
FROM:    Alice Breeveld at MSSL-UCL  <a.breeveld@ucl.ac.uk>

A. A. Breeveld (UCL-MSSL), S. R. Oates (U.Warwick) and J. D. Gropp (PSU)
report on behalf of the Swift/UVOT team:

The Swift/UVOT began settled observations of the field of GRB 180510A 97 
s after the BAT trigger (Gropp et al., GCN Circ. 22695).
A source is detected at the edge of the refined XRT position (D’Ai et 
al. GCN Circ. 22707) but this is consistent with the position of a 
USNO-B1.0 source (at 276.332, -31.908), and it is not clear if we see 
any fading. Preliminary detections and 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            97          247          147         20.0 ± 0.3
white            28989        29010          21          >19.2
v		 22961        23272         301          >19.4
b                28076        28983         885          20.2 ± 0.2
u                  310          322          12          >17.6
uvw1             15854        16753         886          >20.6
uvw2             22055        22955         886          >20.5

The magnitudes in the table are not corrected for the Galactic 
extinction due to the reddening of E(B-V) = 0.26 in the direction of the 
burst (Schlegel et al. 1998).