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fk45

Convert the ra and dec columns of an starbase data table from FK4 to FK5.

        fk45 < file rcol dcol

Convert B1950.0 FK4 star data form the starbase data table read from the standard input to J2000.0 FK5 assuming zero proper motion in an inertial frame (double precision)

Stars positions are converted from the old, Bessel-Newcomb, FK4 system to the new, IAU 1976, FK5, Fricke system, in such a way that the FK5 proper motion is zero. Because such a star has, in general, a non-zero proper motion in the FK4 system, the routine requires the epoch at which the position in the FK4 system was determined.

Convert a J2000.0 FK5 star position form the starbase data table read from the standard input to B1950.0 FK4 assuming zero proper motion and parallax.

Star positions are converted from the new, IAU 1976, FK5, Fricke system to the old, Bessel-Newcomb, FK4 system.

PARAMETERS

• rcol

  The column name of the ra column defaults to "ra". The column should contain RA coordinate values in hours.

• dcol

  The column name of the dec column defaults to "dec". The column should contain Dec coordinate values in degrees.

• bepoch

  The initial position in the B1950 reference frame but at Besselian epoch bepoch. For comparison with catalogues the bepoch argument will frequently be 1950.0 and is the default.

SEE ALSO

• Source text of fk45.
• slalink.1 programs available with the slalink extensions to tawk.
• slalink.4 functions available with the slalink extensions to tawk.
• precess Precess the ra and dec columns from one equinox to another.
• fk54 Convert the ra and dec columns of an starbase data table from FK5 to FK4.

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