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ATEL # 1610; H. A. Krimm (CRESST/GSFC/USRA), J. Kennea (PSU), S. D. Barthelmy (GSFC), W. Baumgartner (CRESST/GSFC/UMBC), J. Cummings (CRESST/GSFC/UMBC), E. Fenimore (LANL), N. Gehrels (GSFC), C. B. Markwardt (CRESST/GSFC/UMD), D. Palmer (LANL), A. Parsons (GSFC), T. Sakamoto (CRESTT/GSFC/UMBC), G. Sato (GSFC/ISAS), G. Skinner (CRESST/GSFC/UMBC), M. Stamatikos (GSFC/ORAU), J. Tueller (GSFC)
on 8 Jul 2008; 20:52 UT
Password Certification: Hans A. Krimm (Hans.Krimm@nasa.gov)
Subjects: X-ray, Request for Observations, Transients
The hard X-ray transient monitor of the Swift Burst Alert Telescope (BAT) has detected a previously unknown galactic transient. This source, Swift J1842.5-1124, was first detected at a daily average rate of 0.005 ± 0.002 counts/sec/cm2 (20 mcrab) in the 15-50 keV band on July 2, 2008 (MJD 54649). It rose to a peak brightness of 0.009 ± 0.002 cts/sec/cm2 (40 mcrab) on July 6 and has remained between 15 and 40 mcrab for the past several days. The best BAT position was RA=280.620, Dec=-11.432, (J2000) with an estimated error of 3'. Note that this source is on the galactic plane at coordinates L=21.735 , B=-3.227 degrees.
On July 7, 2008 beginning at 15:25 UTC, Swift J1842.5-1124 was observed as a target of opportunity with Swift. An X-ray source, Swift J184217.3-112501, was detected at a count rate of 1.61 ± 0.036 cts/s (0.3-10 keV) at a location:
RA(J2000) = 18h 42m 17.33s (280.57221 deg)
Dec(J2000) = -11d 25m 00.6s (-11.41685 deg)
with an estimated error of 1.8'' radius (90% containment). This is 3.0 arc minutes from the BAT position. An examination of the USNO-A2, USNO-B1 and 2MASS catalogs reveals no sources within the error circle.
Swift/BAT light curve for SWIFT J1842.5-1124