The recently discovered transitional millisecond pulsar system J1023+0038 exposes a crucial evolutionary phase of recycled neutron stars for multiwavelength study .
The system , comprising the neutron star itself , its stellar companion , and the surrounding medium , is visible across the electromagnetic spectrum from the radio to X–ray/gamma–ray regimes and offers insight into the recycling phase of millisecond pulsar evolution .
Here , we report on multiple–epoch astrometric observations with the Very Long Baseline Array ( VLBA ) which give a system parallax of 0.731 \pm 0.022 milliarcseconds ( mas ) and a proper motion of 17.98 \pm 0.05 mas yr ^ { -1 } .
By combining our results with previous optical observations , we are able to use the parallax distance of 1368 ^ { +42 } _ { -39 } pc to estimate the mass of the pulsar as 1.71 \pm 0.16 ~ { } M _ { \odot } , and we are also able to measure the 3D space velocity of the system as 126 \pm 5 km s ^ { -1 } .
Despite the precise nature of the VLBA measurements , the remaining \sim 3 % distance uncertainty dominates the 0.16 M _ { \odot } error on our mass estimate .