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/node19.html | 160 +++++++++++++++++++++++++++++++++++++++ 1 file changed, 160 insertions(+) create mode 100644 src/slalib/sun67.htx/node19.html (limited to 'src/slalib/sun67.htx/node19.html') diff --git a/src/slalib/sun67.htx/node19.html b/src/slalib/sun67.htx/node19.html new file mode 100644 index 0000000..3a52cd9 --- /dev/null +++ b/src/slalib/sun67.htx/node19.html @@ -0,0 +1,160 @@ + + + + +SLA_AMPQK - Quick Apparent to Mean + + + + + + + + + + + + +
+ +next + +up + +previous +
+ Next: SLA_AOP - Apparent to Observed +
+Up: SUBPROGRAM SPECIFICATIONS +
+ Previous: SLA_AMP - Apparent to Mean +

+

+

SLA_AMPQK - Quick Apparent to Mean +   +

+
+
ACTION: +
Convert star $[\,\alpha,\delta\,]$ from geocentric apparent to mean place +(post IAU 1976). Use of this routine is appropriate when + efficiency is important and where many star positions are + all to be transformed for one epoch and equinox. The + star-independent parameters can be obtained by calling + the sla_MAPPA routine. +

CALL: +
CALL sla_AMPQK (RA, DA, AMPRMS, RM, DM) +

+

+
GIVEN: +
+
+ + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + +
RA,DADapparent $[\,\alpha,\delta\,]$ (radians)
AMPRMSD(21)star-independent mean-to-apparent parameters:
(1)time interval for proper motion (Julian years)
(2-4)barycentric position of the Earth (AU)
(5-7)heliocentric direction of the Earth (unit vector)
(8)(gravitational radius of +Sun)$\times 2 / $(Sun-Earth distance)
(9-11)v: barycentric Earth velocity in units of c
(12)$\sqrt{1-\left\vert\mbox{\bf v}\right\vert^2}$
(13-21)precession/nutation $3\times3$ matrix
+

+
RETURNED: +
+
+ + + + + +
RM,DMDmean $[\,\alpha,\delta\,]$ (radians)
+

+
NOTES: +
+
1. +
The accuracy is limited by the routine sla_EVP, called +by sla_MAPPA, which computes the Earth position and +velocity using the methods of Stumpff. The maximum + error is about 0.3 milliarcsecond. +
2. +
Iterative techniques are used for the aberration and + light deflection corrections so that the routines + sla_AMP (or sla_AMPQK) and sla_MAP (or sla_MAPQK) are + accurate inverses; even at the edge of the Sun's disc + the discrepancy is only about 1 nanoarcsecond. +
+

+
REFERENCES: +
+
1. +
1984 Astronomical Almanac, pp B39-B41. +
2. +
Lederle & Schwan, 1984. Astr.Astrophys. 134, 1-6. +
+
+ +next + +up + +previous +
+ Next: SLA_AOP - Apparent to Observed +
+Up: SUBPROGRAM SPECIFICATIONS +
+ Previous: SLA_AMP - Apparent to Mean +

+

+

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