Hipparcos to FK5, no P.M.
CALL sla_HFK5Z (RH, DH, EPOCH, R5, D5, DR5, DD5)
RH  D  Hipparcos $\alpha $ (radians) 
 
DH  D  Hipparcos $\delta $ (radians) 


EPOCH  D  Julian epoch (TDB) 
R5  D  J2000.0 FK5 $\alpha $ (radians) 
 
D5  D  J2000.0 FK5 $\delta $ (radians) 


DR5  D  J2000.0 FK5 proper motion in $\alpha $ (radians per Julian year) 


DD5  D  FK5 J2000.0 proper motion in $\delta $ (radians per Julian year) 
orientation  spin
 
$x$  $19.9$  $0.30$ 
$y$  $9.1$  $+0.60$ 
$z$  $+22.9$  $+0.70$ 
mas  mas/y  
These orientation and spin components are interpreted as axial vectors. An axial vector points at the pole of the rotation and its length is the amount of rotation in radians.