GCN Circular 12522

S. D. Barthelmy (GSFC), W. H. Baumgartner (GSFC/UMBC),
D. N. Burrows (PSU), V. D'Elia (ASDC), P. A. Evans (U Leicester),
D. Grupe (PSU), C. Guidorzi (U Ferrara),
S. T. Holland (CRESST/USRA/GSFC), E. A. Hoversten (PSU),
J. A. Kennea (PSU), H. A. Krimm (CRESST/GSFC/USRA),
N. P. M. Kuin (UCL-MSSL), V. Mangano (INAF-IASFPA),
F. E. Marshall (NASA/GSFC), A. Melandri (INAF-OAB),
P. T. O'Brien (U Leicester), K. L. Page (U Leicester),
D. M. Palmer (LANL), C. J. Saxton (UCL-MSSL),
B. Sbarufatti (INAF-OAB/IASFPA), E. Sonbas (GSFC/USRA/Adiyaman Univ.),
R. L. C. Starling (U Leicester), C. A. Swenson (PSU) and
B.-B. Zhang (PSU) report on behalf of the Swift Team:

At 14:12:13 UT, the Swift Burst Alert Telescope (BAT) triggered and
located an event from the known source Swift J1922.7-1716 (trigger=506913). 
Swift slewed immediately to the location. 
The BAT on-board calculated location is 
RA, Dec 290.667, -17.284 which is 
   RA(J2000) = 19h 22m 40s
   Dec(J2000) = -17d 17' 02"
with an uncertainty of 3 arcmin (radius, 90% containment, including 
systematic uncertainty).  The BAT light curve showed a multiple-peaked
structure with a duration of about 30 sec.  The peak count rate
was ~1000 counts/sec (15-350 keV), at ~4 sec after the trigger. 

The XRT began observing the field at 14:14:23.4 UT, 130.2 seconds after
the BAT trigger. XRT found a bright, X-ray source located
at RA, Dec 290.6533, -17.2835 which is equivalent to:
   RA(J2000)  = 19h 22m 36.79s
   Dec(J2000) = -17d 17' 00.6"
with an uncertainty of 5.3 arcseconds (radius, 90% containment). This
location is 47 arcseconds from the BAT onboard position, within the BAT
error circle, and 3.6 arc seconds from the position of Swift J1922.7-1716
reported by Tueller et al. (ATEL #669). No event data are yet available to
determine the column density using X-ray spectroscopy. 

UVOT took a finding chart exposure of 150 seconds with the White 
filter  starting 140 seconds after the BAT trigger. There is a 
candidate optical counterpart in the rapidly available 2.7'x2.7' 
sub-image at  
 RA(J2000)  =	19:22:37.00 = 290.65415  
 DEC(J2000) = -17:17:01.1  = -17.28363  
with a 90%-confidence error radius of about 0.61 arc sec. 
This position is 3.0  arc sec. from the center of the XRT 
error circle. This counterpart is not observed in archival
DSS imaging.  The estimated magnitude is 16.67 with a
1-sigma error of about 0.14. No correction has been made for the  
expected extinction corresponding to E(B-V) of 0.12. 

This source, Swift J1922.7-1716, (Tueller et al., 2005, ATEL #669;
Falanga et al., 2006, A&A v456 pL5), is currently in outburst 
(Nakahira et al., 2011 ATEL #3548; Kennea et al., 2011 #3567) 
and has been slowly rising for the past few months. 
( http://swift.gsfc.nasa.gov/docs/swift/results/transients/SWIFTJ1922.7-1716/ )