The COCO program converts star coordinates from one system to another.
COCO offers control over report resolution, and has a help facility.
All input is free format, and defaults are provided where this is meaningful. In order to comply with the IAU 1976 recommendations, all position data published from 1984 on should be given in the new system, using equinox J2000.0. However, for many years to come positions will be given in the old system, using equinox B1950.0.