We present the result of astrometric observations of the radio pulsar PSR B0656+14 , made using the Very Long Baseline Array .
The parallax of the pulsar is \pi = 3.47 \pm 0.36 mas , yielding a distance 288 ^ { +33 } _ { -27 } pc .
This independent distance estimate has been used to constrain existing models of thermal x-ray emission from the neutron star ’ s photosphere .
Simple blackbody fits to the x-ray data formally yield a neutron star radius R _ { \infty } \sim 7 - 8.5 km .
With more realistic fits to a magnetized hydrogen atmosphere , any radius between \sim 13 and \sim 20 km is allowed .