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GCN Circular 18045

Subject
GRB 150720A: Swift/UVOT Upper Limits
Date
2015-07-22T16:14:07Z (9 years ago)
From
Mike Siegel at PSU/Swift MOC <siegel@swift.psu.edu>
M. H. Siegel (PSU) and E. Sonbas (NASA/GSFC/Adiyaman Univ.)
report on behalf of the Swift/UVOT team:

The Swift/UVOT began settled observations of the field of GRB 150720A
142 s after the BAT trigger (Sonbas et al., GCN Circ. 18037).
No optical afterglow consistent with the XRT position (Beardmore et al.,
GCN Circ. 18040)  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)         142          292          147         >20.5
u (fc)             301          551          246         >20.4
white              142         1551          392         >21.2
v                  631         1601          117         >19.3
b                  557         1527           97         >19.6
u                  301         1502          324         >20.2
w1                 680         1478           97         >19.3
m2                 655         1623          114         >19.8
w2                 606         1577          117         >19.6

The magnitudes in the table are not corrected for the Galactic extinction
due to the reddening of E(B-V) = 0.68 in the direction of the burst
(Schlegel et al. 1998).

[GCN OPS NOTE(22jul15): Added the "A" suffix to the GRB name.]
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