XTE J1807-294 - precise position and orbit determination
ATel #127; C. B. Markwardt (U. Maryland & GSFC), M. Juda (CfA), J. H. Swank (GSFC)
on 16 Mar 2003; 15:21 UT
Distributed as an Instant Email Notice Transients
Credential Certification: Craig B. Markwardt (craigm@lheamail.gsfc.nasa.gov)
Subjects: X-ray, Binary, Neutron Star, Transient, Pulsar
Referred to by ATel #: 148
C. B. Markwardt, University of Maryland and Goddard Space Flight
Center (GSFC), M. Juda, Harvard-Smithsonian Center for Astrophysics,
and J. H. Swank, GSFC report that the Chandra X-ray Observatory
observed XTE J1807-294 on Mar 10.8 (UT), and the best fit position was
determined to be R.A. = 18h06m59.80s, Decl. = -29o24'30" (equinox
2000.0; uncertainty about 1"). On Mar 13.9, RXTE PCA measured a 2-10
keV x-ray flux of 20 mCrab. Pulsations are still detected, and a
orbital Doppler modulation is clearly evident. The best fit orbital
period is 40.0741 +/- 0.0005 minutes, confirming it as the shortest
period of any of the four accreting millisecond pulsars. In light of
the new x-ray position, optical observations are encouraged.
