frame Subroutine

public subroutine frame(pos1, k, pos2)

THIS SUBROUTINE TRANSFORMS A VECTOR FROM THE DYNAMICAL REFERENCE SYSTEM TO THE INTERNATIONAL CELESTIAL REFERENCE SYSTEM (ICRS), OR VICE VERSA. THE DYNAMICAL REFERENCE SYSTEM IS BASED ON THE DYNAMICAL MEAN EQUATOR AND EQUINOX OF J2000.0. THE ICRS IS BASED ON THE SPACE-FIXED ICRS AXES DEFINED BY THE RADIO CATALOG POSITIONS OF SEVERAL HUNDRED EXTRAGALACTIC OBJECTS. THE ROTATION MATRIX USED HERE IS EQUIVALENT TO THAT GIVEN BY HILTON AND HOHENKERK (2004), ASTRONOMY AND ASTROPHYSICS 413, 765-770, EQ. (6) AND (8).

 POS1   = POSITION VECTOR, EQUATORIAL RECTANGULAR
          COORDINATES (IN)
 K      = DIRECTION OF ROTATION (IN)
          SET K < 0 FOR DYNAMICAL TO ICRS
          SET K > 0 FOR ICRS TO DYNAMICAL
 POS2   = POSITION VECTOR, EQUATORIAL RECTANGULAR
          COORDINATES (OUT)

NOTE: FOR GEOCENTRIC COORDINATES, THE SAME TRANSFORMATION IS USED BETWEEN THE DYNAMICAL REFERENCE SYSTEM AND THE GCRS.

Arguments