TITLE:   GCN CIRCULAR
NUMBER:  30040
SUBJECT: GRB 210517A: Swift/UVOT Upper Limits
DATE:    21/05/17 17:35:58 GMT
FROM:    Sam LaPorte at PSU  <sjl5346@psu.edu>

 GRB 210517A: Swift/UVOT Upper Limits

S. J. LaPorte (PSU) and V. D'Elia (SSDC & INAF-OAR)
report on behalf of the Swift/UVOT team:

The Swift/UVOT began settled observations of the field of GRB 210517A
69 s after the BAT trigger (D'Elia et al., GCN Circ. 30032).
No optical afterglow consistent with the optical position
(Tanvir et al. GCN Circ. 30037)
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            69          219          147         >19.4
u_FC               282          531          246         >19.7
white               69         1356          373         >19.9
v                  611         5047          274         >19.0
b                  537         1332           78         >19.5
u                  282         1307          304         >19.7
w1                 661         1109           39         >18.4
m2                5052         5070           18         >18.7
w2                4642         4841          197         >21.1

The magnitudes in the table are not corrected for the Galactic extinction
due to the reddening of E(B-V) = 0.011 in the direction of the burst
(Schlegel et al. 1998).