Towards VLBI Determination of Pulsar Parallaxes, Proper Motions, and Positions.
Session 78 -- Pulsars and Neutron Stars
Display presentation, Wednesday, 11, 1995, 9:20am - 6:30pm

## [78.05] Towards VLBI Determination of Pulsar Parallaxes, Proper Motions, and Positions.

N. Putnam (Brown University), R.M. Campbell (Harvard University), I.I. Shapiro (CfA)

Interleaved VLBI observations of a pulsar and one or more extragalactic phase-reference sources nearby on the sky provide a means to determine their differential positions with sub-milliarcsecond accuracy. Campbell et al. have begun a long-term program to determine the parallax distances, proper motions, and positions of about seven pulsars [see, e.g., Campbell et al. 1993, in Sub-arcsecond Radio Astronomy , ed. R.J. Davis and R.S. Booth (Cambridge: Cambridge University Press), 420]. These results could be used to study the properties of the $\eta_e$ distribution in the solar neighborhood, the calibration of the dispersion-based galactic distance scale, and, when coupled with independent pulse time-of-arrival data, the tie between the extragalactic and dynamic reference frames. Here, we present results of work conducted under the 1994 SAO Summer Intern Program at the CfA within the broader context of the overall goals of the pulsar parallax project.

We acknowledge support from the NSF Research Experiences for Undergraduates Program (NP), NSF grant AST93-03527 (RMC,IIS), and NASA grant NGT-50663 (RMC).