TITLE:   GCN CIRCULAR
NUMBER:  24568
SUBJECT: GRB 190515B: Swift/UVOT Upper Limits
DATE:    19/05/17 03:44:52 GMT
FROM:    Mike Siegel at PSU/Swift MOC  <mhs18@psu.edu>

M. H. Siegel (PSU) and M. J. Moss (George Washington University)
report on behalf of the Swift/UVOT team:

The Swift/UVOT began settled observations of the field of GRB 190515B
93 s after the BAT trigger (Moss et al., GCN Circ. 24553).
No optical afterglow consistent with the XRT position
(Osborne et al. GCN Circ. 24557)
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            93          242          147         >19.9
u_FC               305          555          246         >19.4
white               93          605          167         >20.0
v                  636         4442          216         >18.9
b                  561          754           39         >18.7
u                  305          730          265         >19.5
w1                 685         4722           88         >18.9
m2                 661         4647          216         >19.6
w2                 612         4237          216         >19.0

The magnitudes in the table are not corrected for the Galactic extinction
due to the reddening of E(B-V) = 0.09 in the direction of the burst
(Schlegel et al. 1998).