GCN Circular 15022

Subject
GRB 130722A: Swift/UVOT Detection
Event
Date
2013-07-23T02:38:51Z (13 years ago)
From
Frank Marshall at GSFC <femarsha@khamseen.gsfc.nasa.gov>
F. E. Marshall (NASA/GSFC) and E. Troja (NASA/GSFC/UMCP)
report on behalf of the Swift/UVOT team:

The Swift/UVOT began settled observations of the field of GRB 130722A
120 s after the BAT trigger (Troja et al., GCN Circ. 15013Loading...
 
 ).
A decaying source consistent with the optical position
(Melandri et al. GCN Circ. 15015Loading...
 
 )
is detected in the initial UVOT exposures.
As noted by Melandri et al., there is a catalogued source
near the position of the optical afterglow.
The magnitudes and uncertainties reported below have been
adjusted to accommodate the possibility that the nearby
source accounts for all or none of the UVOT count rate
observed at late times.

The preliminary UVOT position is:
  RA(J2000)  =  17:22:36.47 = 260.65196
  DEC(J2000) = -02:58:21.6  =  -2.97268
with an estimated uncertainty of 0.7 arcsec (radius, 90% confidence).
The uncertainty has been adjusted slightly due to the
possible contamination of the nearby source by up to 10%.

The preliminary detection and 3-sigma upper limits using the UVOT photometric system
(Breeveld et al. 2011, AIP Conf. Proc. 1358, 373) for the early exposures are: 

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

white_FC           120          270          147          19.6 (+0.12/-0.20)
v                 4209         5844          393         >19.7
b                 3594        17728         2039         >20.9
u                  332        16943         2059         >21.0
w1                4619        16030         1218         >21.2
w2                4004         5640          393         >21.3

The magnitudes in the table are not corrected for the Galactic extinction
due to the reddening of E(B-V) = 0.63 in the direction of the burst
(Schlegel et al. 1998).