From d54fe7c1f704a63824c5bfa0ece65245572e9b27 Mon Sep 17 00:00:00 2001 From: Joseph Hunkeler Date: Wed, 4 Mar 2015 21:21:30 -0500 Subject: Initial commit --- src/slalib/sun67.htx/node108.html | 156 ++++++++++++++++++++++++++++++++++++++ 1 file changed, 156 insertions(+) create mode 100644 src/slalib/sun67.htx/node108.html (limited to 'src/slalib/sun67.htx/node108.html') diff --git a/src/slalib/sun67.htx/node108.html b/src/slalib/sun67.htx/node108.html new file mode 100644 index 0000000..504a1a6 --- /dev/null +++ b/src/slalib/sun67.htx/node108.html @@ -0,0 +1,156 @@ + + + + +SLA_FK54Z - FK5 to FK4, no P.M. or Parallax + + + + + + + + + + + + +
+ +next + +up + +previous +
+ Next: SLA_FK5HZ - FK5 to Hipparcos, no P.M. +
+Up: SUBPROGRAM SPECIFICATIONS +
+ Previous: SLA_FK52H - FK5 to Hipparcos +

+

+

SLA_FK54Z - FK5 to FK4, no P.M. or Parallax +   +

+
+
ACTION: +
Convert a J2000.0 FK5 star position to B1950.0 FK4 assuming +FK5 zero proper motion and parallax. + This routine converts star positions from the new, IAU 1976, + FK5, Fricke system to the old, Bessel-Newcomb, FK4 system. +

CALL: +
CALL sla_FK54Z (R2000,D2000,BEPOCH,R1950,D1950,DR1950,DD1950) +

+

+
GIVEN: +
+
+ + + + + + + + + + + + + +
R2000DJ2000.0 FK5 $\alpha$ (radians)
D2000DJ2000.0 FK5 $\delta$ (radians)
BEPOCHDBesselian epoch (e.g. 1950D0)
+

+
RETURNED: +
+
+ + + + + + + + + + + + + + + + + +
R1950DB1950.0 FK4 $\alpha$ at epoch BEPOCH (radians)
D1950DB1950.0 FK4 $\delta$ at epoch BEPOCH (radians)
DR1950DB1950.0 FK4 proper motion in $\alpha$(radians per tropical year)
DD1950DB1950.0 FK4 proper motion in $\delta$(radians per tropical year)
+

+
NOTES: +
+
1. +
The $\alpha$ proper motions are $\dot{\alpha}$ rather than +$\dot{\alpha}\cos\delta$, and are per year rather than per century. +
2. +
Conversion from Julian epoch 2000.0 to Besselian epoch 1950.0 + only is provided for. Conversions involving other epochs will + require use of the appropriate precession routines before and + after this routine is called. +
3. +
Unlike in the sla_FK524 routine, the FK5 proper motions, the + parallax and the radial velocity are presumed zero. +
4. +
It was the intention that FK5 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 FK4, and this routine returns those fictitious proper + motions. +
5. +
The position returned by this routine is in the B1950 + reference frame but at Besselian epoch BEPOCH. For + comparison with catalogues the BEPOCH argument will + frequently be 1950D0. +
6. +
See also sla_FK425, sla_FK45Z, sla_FK524. +
+
+ +next + +up + +previous +
+ Next: SLA_FK5HZ - FK5 to Hipparcos, no P.M. +
+Up: SUBPROGRAM SPECIFICATIONS +
+ Previous: SLA_FK52H - FK5 to Hipparcos +

+

+

+SLALIB --- Positional Astronomy Library
Starlink User Note 67
P. T. Wallace
12 October 1999
E-mail:ptw@star.rl.ac.uk +
+ + -- cgit