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IGR J19294+1816 is an X-ray Pulsar

ATel #2002; T. Strohmayer (NASA/GSFC), J. Rodriquez (CEA Saclay), C. Markwardt (UMD/CRESST), J. Tomsick (SSL, Berkeley), A. Bodaghee (Univ. Geneva), S. Chaty, S. Corbel (CEA Saclay & Univ. Paris Diderot), A. Paizis (INAF, Milano)
on 2 Apr 2009; 04:35 UT
Credential Certification: Tod Strohmayer (tod.strohmayer@nasa.gov)

Subjects: X-ray, Binary, Neutron Star, Pulsar

Referred to by ATel #: 2008, 4135, 13215

RXTE observed the new INTEGRAL source IGR J19294+1816 (ATEL #1997) for 2.5 ksec starting on March 31, 2009 at 07:51:28 (UT). A second 3.2 ksec observation began at 17:02:24 (UT) on the same day. We detect strong pulsations in the first observation with a barycentric period of 12.44 s. The background subtracted, average pulsation amplitude during this observation is 37%. We also detect the first harmonic, but with an amplitude smaller by a factor of approximately 4. This confirms the preliminary indications obtained with Swift/XRT (ATEL #1998), and that the object is most likely an accreting pulsar. The phase-averaged flux from the source is highly variable, with a mean intensity of about 5 cts/sec/PCU, but with excursions in the range from 1 - 30 cts/sec/PCU. The mean intensity corresponds to a flux of approximately 2 mCrab in the PCA band. There is some indication in the first observation that the phase-averaged variability is quasiperiodic, with variations on a time-scale near 190 seconds. The energy spectrum is well modeled by a power law, with photon index which varies over time in the range 1.5 - 1.9, and an iron line at 6.4 keV with equivalent width 360 eV. The fluxes in the 2-10, 10-20 and 20-40 keV bands are in the ranges 3.4-4.7, 1.6-3.4, and 1.7-4.8, respectively, in units of 1e-11 erg/s/cm2. Additional observations with RXTE are planned.