TITLE: GCN CIRCULAR NUMBER: 12522 SUBJECT: Trigger 506913: Swift detection of Swift J1922.7-1716 and its optical counterpart DATE: 11/11/03 14:37:59 GMT FROM: David Palmer at LANL 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/ )