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GCN Circular 26690

GRB 200109A: Swift/UVOT Upper Limits
2020-01-09T19:26:41Z (4 years ago)
Kira Simpson at PSU <>
GRB 200109A: Swift/UVOT Upper Limits

K. K. Simpson (PSU) and A. Melandri (INAF-OAB)
report on behalf of the Swift/UVOT team:

The Swift/UVOT began settled observations of the field of GRB 200109A
110 s after the BAT trigger (Melandri et al., GCN Circ. 26678).
No optical afterglow consistent with the XRT position
(Melandri et al. GCN Circ. 26678)
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           110          259          147         >20.5
u_FC               268          518          246         >19.0
white              110         1023          295         >20.9
u                  268          518          246         >19.0

The magnitudes in the table are not corrected for the Galactic extinction
due to the reddening of E(B-V) = 0.29 in the direction of the burst
(Schlegel et al. 1998).
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