TITLE: GCN CIRCULAR NUMBER: 10561 SUBJECT: Swift detection of LS V +44 17 DATE: 10/04/01 19:51:03 GMT FROM: David Palmer at LANL G. Stratta (ASDC), W. H. Baumgartner (GSFC/UMBC), S. Campana (INAF-OAB), P. A. Curran (UCL-MSSL), V. D'Elia (ASDC), N. Gehrels (NASA/GSFC), J. M. Gelbord (PSU), S. T. Holland (CRESST/USRA/GSFC), E. A. Hoversten (PSU), J. A. Kennea (PSU), W.B Landsman (GSFC), J. Mao (INAF-OAB), C. B. Markwardt (CRESST/GSFC/UMD), D. M. Palmer (LANL), M. H. Siegel (PSU), M. Stamatikos (OSU/NASA/GSFC), M. A. Stark (PSU), R. L. C. Starling (U Leicester) and E. Troja (NASA/GSFC/ORAU) report on behalf of the Swift Team: At 18:34:10 UT, the Swift Burst Alert Telescope (BAT) triggered and located trigger 418109. Swift slewed to the location at the end of the trigger image interval. The BAT on-board calculated location is RA, Dec 70.262, +44.512 which is RA(J2000) = 04h 41m 03s Dec(J2000) = +44d 30' 44" with an uncertainty of 3 arcmin (radius, 90% containment, including systematic uncertainty). This is an image trigger (30 minute duration). The position is consistent with the known Be X-ray pulsar LS V +44 17, which was recently reported to be active (Morii et al, ATEL #2527). BAT has been detecting this source with marginal significance over the past few days, with the first detection (~60 mCrab) on 2010 March 29 at 21:39 UT. The XRT began observing the field at 19:08:39.4 UT, 2069.0 seconds after the BAT trigger. XRT found a bright X-ray source located at RA, Dec 70.2497, +44.5297 which is equivalent to: RA(J2000) = 04h 41m 00.07s Dec(J2000) = +44d 31' 46.9" with an uncertainty of 5.2 arcseconds (radius, 90% containment). This location is 71 arcseconds from the BAT onboard position, within the BAT error circle. XRT position is consistent with LS V +44 17. No event data are yet available to determine the column density using X-ray spectroscopy. The initial flux in the 2.5 s image was 1.60e-09 erg cm^-2 s^-1 (0.2-10 keV). UVOT took a finding chart exposure of 150 seconds with the White filter starting 2080 seconds after the BAT trigger. LS V +44 17 is bright at the XRT position and compromised by coincidence loss at a level which is uncorrectable. The SIMBAD magnitude for the source is V = 10.7, which is consistent with the UVOT image although more quantitative statements cannot be made.