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GCN Circular 18218

Subject
GRB 150831A: Swift/UVOT Upper Limits
Date
2015-09-01T00:14:09Z (9 years ago)
From
Mike Siegel at PSU/Swift MOC <siegel@swift.psu.edu>
M. H. Siegel (PSU) and A. Y. Lien (GSFC/UMBC)
report on behalf of the Swift/UVOT team:

The Swift/UVOT began settled observations of the field of GRB 150831A
88 s after the BAT trigger (Lien et al., GCN Circ. 18209).
No optical afterglow consistent with the XRT position
(Osborne et al. GCN Circ. 18212)
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            88          238          147         >20.5
u_FC               300          550          246         >19.9
white               88         6622          746         >21.2
v                  631        17885         1356         >19.8
b                  557         6417          452         >20.4
u                  300        12784         1326         >21.0
w1                 680        12112         1153         >21.3
m2                 655        18529         1750         >21.3
w2                 607        16972         1357         >21.1

The magnitudes in the table are not corrected for the Galactic extinction
due to the reddening of E(B-V) = 0.11 in the direction of the burst
(Schlegel et al. 1998).
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