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/node104.html | 208 ++++++++++++++++++++++++++++++++++++++ 1 file changed, 208 insertions(+) create mode 100644 src/slalib/sun67.htx/node104.html (limited to 'src/slalib/sun67.htx/node104.html') diff --git a/src/slalib/sun67.htx/node104.html b/src/slalib/sun67.htx/node104.html new file mode 100644 index 0000000..0a2f9ca --- /dev/null +++ b/src/slalib/sun67.htx/node104.html @@ -0,0 +1,208 @@ + + + + +SLA_FK425 - FK4 to FK5 + + + + + + + + + + + + +
+ +next + +up + +previous +
+ Next: SLA_FK45Z - FK4 to FK5, no P.M. or Parallax +
+Up: SUBPROGRAM SPECIFICATIONS +
+ Previous: SLA_FITXY - Fit Linear Model to Two Sets +

+

+

SLA_FK425 - FK4 to FK5 +   +

+
+
ACTION: +
Convert B1950.0 FK4 star data to J2000.0 FK5. +This routine converts stars from the old, Bessel-Newcomb, FK4 + system to the new, IAU 1976, FK5, Fricke system. The precepts + of Smith et al. (see reference 1) are followed, + using the implementation + by Yallop et al. (reference 2) of a matrix method + due to Standish. + Kinoshita's development of Andoyer's post-Newcomb precession is + used. The numerical constants from + Seidelmann et al. (reference 3) are used canonically. +

CALL: +
CALL sla_FK425 ( + R1950,D1950,DR1950,DD1950,P1950,V1950, + R2000,D2000,DR2000,DD2000,P2000,V2000) +

+

+
GIVEN: +
+
+ + + + + + + + + + + + + + + + + + + + + + + + + +
R1950DB1950.0 $\alpha$ (radians)
D1950DB1950.0 $\delta$ (radians)
DR1950DB1950.0 proper motion in $\alpha$(radians per tropical year)
DD1950DB1950.0 proper motion in $\delta$(radians per tropical year)
P1950DB1950.0 parallax (arcsec)
V1950DB1950.0 radial velocity (km s-1, +ve = moving away)
+

+
RETURNED: +
+
+ + + + + + + + + + + + + + + + + + + + + + + + + +
R2000DJ2000.0 $\alpha$ (radians)
D2000DJ2000.0 $\delta$ (radians)
DR2000DJ2000.0 proper motion in $\alpha$(radians per Julian year)
DD2000DJ2000.0 proper motion in $\delta$(radians per Julian year)
P2000DJ2000.0 parallax (arcsec)
V2000DJ2000.0 radial velocity (km s-1, +ve = moving away)
+

+
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 Besselian epoch 1950.0 to Julian epoch + 2000.0 only is provided for. Conversions involving other + epochs will require use of the appropriate precession, + proper motion, and E-terms routines before and/or after FK425 + is called. +
3. +
In the FK4 catalogue the proper motions of stars within + $10^{\circ}$ of the poles do not include the differential + E-terms effect and should, strictly speaking, be handled + in a different manner from stars outside these regions. + However, given the general lack of homogeneity of the star + data available for routine astrometry, the difficulties of + handling positions that may have been determined from + astrometric fields spanning the polar and non-polar regions, + the likelihood that the differential E-terms effect was not + taken into account when allowing for proper motion in past + astrometry, and the undesirability of a discontinuity in + the algorithm, the decision has been made in this routine to + include the effect of differential E-terms on the proper + motions for all stars, whether polar or not. At epoch J2000, + and measuring on the sky rather than in terms of $\Delta\alpha$, the errors resulting from this simplification are less than + 1 milliarcsecond in position and 1 milliarcsecond per + century in proper motion. +
4. +
See also sla_FK45Z, sla_FK524, sla_FK54Z. +
+

+
REFERENCES: +
+
1. +
Smith, C.A. et al., 1989. Astr.J. 97, 265. +
2. +
Yallop, B.D. et al., 1989. Astr.J. 97, 274. +
3. +
Seidelmann, P.K. (ed), 1992. Explanatory + Supplement to the Astronomical Almanac, ISBN 0-935702-68-7. +
+
+ +next + +up + +previous +
+ Next: SLA_FK45Z - FK4 to FK5, no P.M. or Parallax +
+Up: SUBPROGRAM SPECIFICATIONS +
+ Previous: SLA_FITXY - Fit Linear Model to Two Sets +

+

+

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