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GCN Circular 12286

GRB 110818A: Swift/UVOT Upper Limits
2011-08-19T19:29:06Z (13 years ago)
Tyler Pritchard at PSU <>
T. A. Pritchard (PSU) and C. B. Markwardt (NASA/GSFC)
report on behalf of the Swift/UVOT team:

The Swift/UVOT began settled observations of the field of GRB 110818A
379 s after the BAT trigger (Markwardt et al., GCN Circ. 12279).
No optical afterglow consistent with the Enhanced Swift-XRT position
(GCN Circ. 12285) is detected in the initial UVOT exposures.
Preliminary 3-sigma upper limits using the UVOT photometric system
(Poole et al. 2008, MNRAS, 383, 627) for the initial exposures are:

Filter         T_start(s)   T_stop(s)      Exp(s)         Mag

v                  379        14423         1513         >20.8
b                  477        18642         2455         >22.2
u                  452         8009          813         >20.4
w1                 428         7804          646         >20.9
m2                7399         7599          197         >20.9
w2                6989        13752         1082         >21.2

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).
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