precess (in) (out)

  read a series of RA,DEC coordinate pairs (in decimal degrees) and
  precess them from the (in) equinox to the (out) equinox.  Equinoxes
  are decimal years in the J2000 system, or in the B1950 system if
  prepended by 'B'.  B and J may be used to substitude for B1950 and
  J2000 respectively.