Masses, Parallax, and Relativistic Timing of the PSR J1713+0747 Binary   System
  We report on 12 years of observations of PSR J1713+0747, a pulsar in a 68-day orbit with a white dwarf. Pulse times of arrival were measured with uncertainties as small as 200 ns. The timing data yielded measurements of the relativistic Shapiro delay, perturbations of pulsar orbital elements due to secular and annual motion of the Earth, and the pulsar's parallax, as well as pulse spin-down, astrometric, and Keplerian measurements. The observations constrain the masses of the pulsar and secondary star to be m1=1.3+-0.2 solar masses and m2=0.28+-0.03 solar masses, respectively (68% confidence). Combining the theoretical orbital period-core mass relation with the observational constraints yields a somewhat higher pulsar mass, m1=1.53-0.06+0.08 solar masses. The parallax is 0.89+-0.08 mas, corresponding to a distance of 1.1+-0.1 kpc; the precision of the parallax measurement is limited by uncertainties in the electron content of the solar wind. The transverse velocity is unusually small, 33+-3 km/s. We find significant timing noise on time scales of several years, but no more than expected by extrapolating timing noise statistics from the slow pulsar population. With the orientation of the binary orbit fully measured, we are able to improve on previous tests of equivalence principle violations. 
Eric M. Splaver, David J. Nice (Princeton), Ingrid H. Stairs (UBC),   Andrea N. Lommen (F and M), Donald C. Backer (UC Berkeley)