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Swift J1816.7-1613 is a 143 s HMXB Pulsar

ATEL # 1457; J. P. Halpern, E. V. Gotthelf (Columbia U.)
on 3 Apr 2008; 1:32 UT
Password Certification: Jules Halpern (

Subjects: X-ray, Binaries, Neutron Stars, Pulsars
Referred to by ATEL #: 1462

The transient X-ray source Swift J1816.7-1613 announced by Krimm et al. (ATel #1456) was also detected serendipitously in a 16 ks Chandra ACIS observation on 2007 February 11. Its position is 18h16m42.66s, -16d13'23.4" (J2000), not consistent with the USNO star mentioned in ATel #1456. Its spectrum can be fitted by a power law of photon index Gamma = 1.2+/-0.5 and column density N_H = (12+/-3)x10^{22} cm^{-2}. The 2-10 keV flux is 4x10^{-12} ergs cm^{-2} s^{-1}. We find a highly pulsed signal at a barycentric period of 142.9+/-0.2 s. Evidently a high mass X-ray binary pulsar, this source was also detected by XMM-Newton at a low flux of 7x10^{-13} ergs cm^{-2} s^{-1} as 2XMM J181642.7-161320 on 2003 March 8.

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