[vsnet-grb-info 28607] GRB 210822A: Swift/UVOT Detection

[GCN Circulars]

TITLE:   GCN CIRCULAR
NUMBER:  30710
SUBJECT: GRB 210822A: Swift/UVOT Detection
DATE:    21/08/25 06:21:36 GMT
FROM:    Mike Siegel at PSU/Swift MOC  <mhs18 at 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 210822A
85 s after the BAT trigger (Page et al., GCN Circ. 30677).
A fading source consistent with the XRT position (Page et al.
GCN Circ. 30677) and the previously reported UVOT source is 
is detected in the initial UVOT exposures.

Preliminary detections and 3-sigma upper limits using the UVOT photometric system
(Breeveld et al. 2011, AIP Conf. Proc. 1358, 373) for the early exposures are: 

Filter         T_start(s)   T_stop(s)      Exp(s)           Mag
white (fc)          86          236          147      13.63+/-1.10
white              577         1200          205      15.35+/-0.02
white             4965         5058           91      17.43+/-0.05
white            34405        35230          804      19.15+/-0.05
white           149533       190336         1894      20.64+/-0.11
v                  627         1250           77      15.07+/-0.05
v                27494        28215          702      18.68+/-0.13
b                  553         1176           58      15.31+/-0.04
b                 4760         4960          196      17.56+/-0.06
b                33493        34400          885      19.18+/-0.08
u (fc)             298          548          245      13.78+/-0.03
u                  700         1304           39      14.86+/-0.05
u                 4555         4755          196      16.85+/-0.05
u                57947        58635          670      19.73+/-0.19
uvw1               676         1299           77      15.28+/-0.07
uvw1             39434        96567         1775      19.90+/-0.22
uvm2               824         1274           38            >17.66
uvm2             92215        93015          788            >20.06
uvw2               602         1225           77      17.21+/-0.18
uvw2             21659        64335         1469      20.40+/-0.34

The magnitudes in the table are not corrected for the Galactic extinction
due to the reddening of E(B-V) = 0.162 in the direction of the burst
(Schlegel et al. 1998).