SLA_MOON - Approx Moon Pos/Vel

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/node130.html | 140 ++++++++++++++++++++++++++++++++++++++ 1 file changed, 140 insertions(+) create mode 100644 src/slalib/sun67.htx/node130.html (limited to 'src/slalib/sun67.htx/node130.html') diff --git a/src/slalib/sun67.htx/node130.html b/src/slalib/sun67.htx/node130.html new file mode 100644 index 0000000..99d6086 --- /dev/null +++ b/src/slalib/sun67.htx/node130.html @@ -0,0 +1,140 @@ + + + + +SLA_MOON - Approx Moon Pos/Vel + + + + + + + + + + + + +

+ +

+
+ Next: SLA_MXM - Multiply Matrices +
+Up: SUBPROGRAM SPECIFICATIONS +
+ Previous: SLA_MAPQKZ - Quick Mean-Appt, no PM etc. +

SLA_MOON - Approx Moon Pos/Vel + +

ACTION: +: Approximate geocentric position and velocity of the Moon +(single precision). +
CALL: +: CALL sla_MOON (IY, ID, FD, PV) +

GIVEN: +

+
+ + + + + + + + + + + + + +

IY	I	year
ID	I	day in year (1 = Jan 1st)
FD	R	fraction of day

RETURNED: +

+
+ + + + + +

PV	R(6)	Moon $[\,x,y,z,\dot{x},\dot{y},\dot{z}\,]$ , mean equator and equinox of +date (AU, AU s^-1)

NOTES: +

1. +

The date and time is TDB (loosely ET) in a Julian calendar +which has been aligned to the ordinary Gregorian +calendar for the interval 1900 March 1 to 2100 February 28. + The year and day can be obtained by calling sla_CALYD or + sla_CLYD. +

2. +

The position is accurate to better than 0.5 arcminute + in direction and 1000 km in distance. The velocity + is accurate to better than + $0\hspace{-0.05em}^{'\hspace{-0.1em}'}\hspace{-0.4em}.5$ per hour in direction + and 4 metres per socond in distance. (RMS figures with respect + to JPL DE200 for the interval 1960-2025 are $14\hspace{-0.05em}^{'\hspace{-0.1em}'}$ and +

$0\hspace{-0.05em}^{'\hspace{-0.1em}'}\hspace{-0.4em}.2$ per hour in longitude, $9\hspace{-0.05em}^{'\hspace{-0.1em}'}$ and + $0\hspace{-0.05em}^{'\hspace{-0.1em}'}\hspace{-0.4em}.2$

+per hour in latitude, 350 km and 2 metres per second in distance.) + Note that the distance accuracy is comparatively poor because this + routine is principally intended for computing topocentric direction. +

3. +

This routine is only a partial implementation of the original + Meeus algorithm (reference below), which offers 4 times the + accuracy in direction and 20 times the accuracy in distance + when fully implemented (as it is in sla_DMOON). +

REFERENCE: +: Meeus, l'Astronomie, June 1984, p348. +

+ +

+
+ Next: SLA_MXM - Multiply Matrices +
+Up: SUBPROGRAM SPECIFICATIONS +
+ Previous: SLA_MAPQKZ - Quick Mean-Appt, no PM etc. +

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

+ + -- cgit