VLBI-DERIVED TRIGONOMETRIC PARALLAX AND PROPER MOTION OF PSR B2021+51

摘要

We present the first results from a long-term program to measure the trigonometric parallaxes and proper motions of a set of pulsars using VLBI. We obtained these results for PSR B2021+51 from four sessions of S-band observations of the pulsar and associated reference sources. We estimate a parallax of 0.95 ± 0.37 mas, a proper motion of μ_α = -8.11 ± 0.24 mas yr~(-1) and μ_δ = +13.41 ± 0.25 mas yr~(-1), and a position at epoch 1992.723 of α = 20h22m49.87031s ± 0.00004s and δ = 51°54?50.2913″± 0.0003″(all J2000). Our parallax estimate implies an average electron density of 0.021 ± 0.008 cm~(-3) along the line of sight to the pulsar. We also effectively rule out a physical association with the supernova remnant HB 21.