### SLA_HFK5Z

Hipparcos to FK5, no P.M.

ACTION:
Transform a Hipparcos star position into the FK5 (J2000) frame assuming zero Hipparcos proper motion.
CALL:
CALL sla_HFK5Z (RH, DH, EPOCH, R5, D5, DR5, DD5)
##### GIVEN:
 RH D Hipparcos $\alpha$ (radians) DH D Hipparcos $\delta$ (radians) EPOCH D Julian epoch (TDB)

##### RETURNED:
 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)

NOTES:
(1)
The $\alpha$ proper motions are $\stackrel{̇}{\alpha }$ rather than $\stackrel{̇}{\alpha }cos\delta$, and are per year rather than per century.
(2)
The FK5 to Hipparcos transformation consists of a pure rotation and spin; zonal errors in the FK5 catalogue are not taken into account.
(3)
The adopted epoch J2000.0 FK5 to Hipparcos orientation and spin values are as follows (see reference):

 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.

(4)
It was the intention that Hipparcos should be a close approximation to an inertial frame, so that distant objects have zero proper motion; such objects have (in general) non-zero proper motion in FK5, and this routine returns those fictitious proper motions.
(5)
The position returned by this routine is in the FK5 J2000 reference frame but at Julian epoch EPOCH.
(6)