{
  "bibcode": "2010GCN.10834....1D",
  "body": "M. De Pasquale (UCL-MSSL), A. P. Beardmore (U Leicester),\nD. N. Burrows (PSU), P. A. Curran (UCL-MSSL), V. D'Elia (ASDC),\nP. A. Evans (U Leicester), J. M. Gelbord (PSU),\nC. Guidorzi (U Ferrara), S. T. Holland (CRESST/USRA/GSFC),\nJ. A. Kennea (PSU), O. M. Littlejohns (U Leicester),\nV. Mangano (INAF-IASFPA), J. Mao (INAF-OAB), R. Margutti (INAF-OAB),\nS. R. Oates (UCL-MSSL), J. P. Osborne (U Leicester),\nC. Pagani (U Leicester), K. L. Page (U Leicester),\nP. Romano (INAF-IASFPA), A. Rowlinson (U Leicester),\nM. H. Siegel (PSU), M. Stamatikos (OSU/NASA/GSFC),\nR. L. C. Starling (U Leicester), T. N. Ukwatta (GSFC/GWU) and\nL. Vetere (PSU) report on behalf of the Swift Team:\n\nAt 11:20:42 UT, the Swift Burst Alert Telescope (BAT) triggered on the cataloged\nsource XTE J1946+274 (trigger=424161).  Swift slewed to the source as soon as\nthe BAT detected it as an image trigger.  The BAT on-board calculated location is \nRA, Dec 296.430, +27.366 which is \n   RA(J2000) = 19h 45m 43s\n   Dec(J2000) = +27d 21' 57\"\nwith an uncertainty of 3 arcmin (radius, 90% containment, including \nsystematic uncertainty). \n\nThe XRT began observing the field at 11:51:28.2 UT, 1846.1 seconds\nafter the BAT trigger. Using promptly downlinked data we find a bright\nX-ray source located at RA, Dec 296.41360, 27.36422 which is equivalent\nto:\n   RA(J2000)  = 19h 45m 39.26s\n   Dec(J2000) = +27d 21' 51.2\"\nwith an uncertainty of 3.8 arcseconds (radius, 90% containment). This\nlocation is 53 arcseconds from the BAT onboard position, within the\nBAT error circle. This is 4.5 arcsec from the position of XTE J1946+274\n(2MASS J19453935+2721555).  The XRT position may be improved as more \ndata are received; the latest position is available at \nhttp://www.swift.ac.uk/sper. \n\nA power-law fit to a spectrum formed from promptly downlinked event\ndata gives a column density in excess of the Galactic value (9.43e+21\ncm^-2, Kalberla et al. 2005), with an excess column of 7.8\n(+9.36/-7.22) x 10^21 cm^-2 (90% confidence). \n\nThe initial flux in the 2.5 s image was 7.09e-10 erg cm^-2 s^-1 (0.2-10\nkeV). \n\nUVOT took a finding chart exposure of 150 seconds with the White filter\nstarting 1854 seconds after the BAT trigger. No credible optical transient\nhas been found in the initial data products. The 2.7'x2.7' sub-image covers\n100% of the XRT error circle. Because of the density of catalogued stars,\nfurther analysis is required to report an upper limit for any afterglow in the\nsub-image. No correction has been made for the large, but uncertain\nextinction expected.",
  "circularId": 10834,
  "createdOn": 1275999191000,
  "email": "dxb15@psu.edu",
  "subject": "Trigger 424161: Swift/BAT trigger on XTE J1946+274/GRO J1944+26",
  "submitter": "David Burrows at PSU/Swift  <dxb15@psu.edu>"
}