TITLE:   GCN CIRCULAR
NUMBER:  28050
SUBJECT: GRB 200630A: Swift/UVOT Upper Limits 
DATE:    20/07/01 02:15:16 GMT
FROM:    Mike Siegel at PSU/Swift MOC  <mhs18@psu.edu>

M. H. Siegel (PSU) and K. L. Page (U. Leicester)
report on behalf of the Swift/UVOT team:

The Swift/UVOT began settled observations of the field of GRB 200630A
83 s after the BAT trigger (Page et al., GCN Circ. 28043).
No optical afterglow consistent with the XRT position
(Page et al. GCN Circ. 28043)
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            83          233          147         >19.7
u_FC               295          545          246         >19.8
white               83         1189          353         >20.4
v                  624         1239           78         >18.9
b                  550         1164           58         >19.6
u                  295         5310          433         >20.1
w1                 674         5154          253         >20.1
m2                 822         4949          232         >20.5
w2                 600         1214           78         >20.0

The magnitudes in the table are not corrected for the Galactic extinction
due to the reddening of E(B-V) = 0.04 in the direction of the burst
(Schlegel et al. 1998).