A Refined Orbital Solution for Swift J1749.4-2807
ATel #2569; T. E. Strohmayer (NASA/GSFC), C. B. Markwardt (U. Maryland & NASA/GSFC)
on 16 Apr 2010; 21:29 UT
Credential Certification: Tod Strohmayer (tod.strohmayer@nasa.gov)
Subjects: X-ray, Binary, Neutron Star, Transient, Pulsar
We report a refined orbital solution for the new accreting ms pulsar
Swift J1749.4-2807 (ATEL #2548, #2567, #2568), using 14 ks of barycenter-corrected
RXTE data spanning the time range 2010-04-14T21:12 to 2010-04-16T17:24
(UTC).
We obtained a coherent, phase connected timing
solution with a circular orbit model. We find an orbital period of
31740.345 +- 0.04 s (8.8168 hr), a projected semi-major axis of
a sin(i) = 1899.53 +- 0.01 lt-ms, and a barycentric pulse frequency
for the first harmonic of the pulsar (twice the spin
frequency) of 1035.840025 +- 0.4 micro-Hz. The time of the ascending
node is 2455301.1522672 ± 0.0000014 JD (TDB).
This solution implies a mass function of 0.05463 +- 0.00018 M_sol,
and a minimum companion mass of 0.475 (for a 1.4 M_sol neutron star).
The most recent observations indicate that the amplitude of the fundamental
has increased again. Additional RXTE observations are planned. Observations
at other wavelengths are encouraged.
