Pulsar PSR 1744-24A - Timing, eclipses, and the evolution of neutron star binaries

This paper presents an analysis of 1.7 yrs of high-precision timing measurements of the millisecond pulsar PSR 1744-24A. The timing position of the pulsar shows it to be 40 arcsec from the core of the globular cluster Terzan 5, coincident with a steep-spectrum continuum source. The observed negative pulsar period derivative of -1.9 +/- 0.2 x 10 exp -20 is biased by acceleration of the system in the gravitational fields of the cluster and possibly the Galactic center. A strong attenuation of the pulsed signal occurs near the eclipse edges, and excess time delays of the pulsed signal are observed during eclipses. Eclipse characteristics vary as a function of frequency and, even at a single frequency, orbital phases of eclipse edges are somewhat variable. The upper limit on changes in the orbital period puts a lower limit of 40 Myr on the time scale of orbital evolution. The implications of these observations are discussed.