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GCN Circular 25450

GRB 190821A: Swift/UVOT Upper Limits
2019-08-22T17:58:31Z (5 years ago)
Kira Simpson at PSU <>
GRB 190821A: Swift/UVOT Upper Limits

K. K. Simpson (PSU) and A. D'Ai (INAF-IASFPA)
report on behalf of the Swift/UVOT team:

The Swift/UVOT began settled observations of the field of GRB 190821A
89 s after the BAT trigger (D'Ai et al., GCN Circ. 25427).
No optical afterglow consistent with the XRT position
(Goad et al. GCN Circ. 25436)
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            89          239          147         >19.1
white               89         5595          344         >19.5
v                 5806         6006          197         >18.3
b                 5191         5390          197         >19.9
u                  303        11409          336         >19.6
w1                9373         9551          175         >18.9
m2                6011         6164          151         >19.7
w2                5602         5801          197         >20.2

The magnitudes in the table are not corrected for the Galactic extinction
due to the reddening of E(B-V) = 0.53 in the direction of the burst
(Schlegel et al. 1998).
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