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GCN Circular 20851

Subject
GRB 170311A: Swift/UVOT Upper Limits
Date
2017-03-12T02:10:46Z (8 years ago)
From
Mike Siegel at PSU/Swift MOC <siegel@swift.psu.edu>
M. H. Siegel (PSU) and J. R. Cummings (NASA/UMBC)
report on behalf of the Swift/UVOT team:

The Swift/UVOT began settled observations of the field of GRB 170311A
110 s after the BAT trigger (Cummings et al., GCN Circ. 20846).
No optical afterglow consistent with the XRT position
(Cummings et al. GCN Circ. 20846)
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               269          519          246         >19.7
white              110         7074          645         >21.2
v                  600        11424         1022         >20.3
b                  525         5585          294         >20.1
u                  269         5380          537         >20.1
w1                 650         5175          279         >20.1
m2                 624        13058           82         >20.1
w2                 575         7280          313         >20.2

The magnitudes in the table are not corrected for the Galactic extinction
due to the reddening of E(B-V) = 0.16 in the direction of the burst
(Schlegel et al. 1998).
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