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GCN Circular 31328

Subject
GRB 211227A: Swift/UVOT Upper Limits
Date
2021-12-28T19:38:09Z (2 years ago)
From
Alexander Belles at PSU/Swift <aub1461@psu.edu>
A. Belles (PSU) and A. P. Beardmore (U. Leicester)
report on behalf of the Swift/UVOT team:

The Swift/UVOT began settled observations of the field of GRB 211227A
82 s after the BAT trigger (Beardmore et al., GCN Circ. 31316).
No optical afterglow consistent with the XRT position
(Goad et al. GCN Circ. 31322)
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            82          232          147         >19.4
u_FC               294          544          246         >19.2
white               82         1021          334         >19.5
v                  624         4923          241         >18.7
b                  550          742           39         >18.6
u                  294         5431          357         >19.4
w1                 673         5333          235         >19.7
m2                 648         5127          235         >20.4
w2                 772          792           19         >19.0

The magnitudes in the table are not corrected for the Galactic extinction
due to the reddening of E(B-V) = 0.020 in the direction of the burst
(Schlegel et al. 1998).
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