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/node62.html | 154 +++++++++++++++++++++++++++++++++++++++ 1 file changed, 154 insertions(+) create mode 100644 src/slalib/sun67.htx/node62.html (limited to 'src/slalib/sun67.htx/node62.html') diff --git a/src/slalib/sun67.htx/node62.html b/src/slalib/sun67.htx/node62.html new file mode 100644 index 0000000..dedceda --- /dev/null +++ b/src/slalib/sun67.htx/node62.html @@ -0,0 +1,154 @@ + + + + +SLA_DMOON - Approx Moon Pos/Vel + + + + + + + + + + + + +
+ +next + +up + +previous +
+ Next: SLA_DMXM - Multiply Matrices +
+Up: SUBPROGRAM SPECIFICATIONS +
+ Previous: SLA_DMAT - Solve Simultaneous Equations +

+

+

SLA_DMOON - Approx Moon Pos/Vel +   +

+
+
ACTION: +
Approximate geocentric position and velocity of the Moon +(double precision). +

CALL: +
CALL sla_DMOON (DATE, PV) +

+

+
GIVEN: +
+
+ + + + + +
DATEDTDB (loosely ET) as a Modified Julian Date (JD-2400000.5) +
+

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

+
NOTES: +
+
1. +
This routine is a full implementation of the algorithm +published by Meeus (see reference). +
2. +
Meeus quotes accuracies of $10\hspace{-0.05em}^{'\hspace{-0.1em}'}$ in longitude, + $3\hspace{-0.05em}^{'\hspace{-0.1em}'}$ in latitude and + $0\hspace{-0.05em}^{'\hspace{-0.1em}'}\hspace{-0.4em}.2$ arcsec in HP + (equivalent to about 20 km in distance). Comparison with + JPL DE200 over the interval 1960-2025 gives RMS errors of +

$3\hspace{-0.05em}^{'\hspace{-0.1em}'}\hspace{-0.4em}.7$ and 83 mas/hour in longitude, +

$2\hspace{-0.05em}^{'\hspace{-0.1em}'}\hspace{-0.4em}.3$ arcsec and 48 mas/hour in latitude, + 11 km and 81 mm/s in distance. + The maximum errors over the same interval are + $18\hspace{-0.05em}^{'\hspace{-0.1em}'}$ and + $0\hspace{-0.05em}^{'\hspace{-0.1em}'}\hspace{-0.4em}.50$ /hour in longitude, + $11\hspace{-0.05em}^{'\hspace{-0.1em}'}$ and + $0\hspace{-0.05em}^{'\hspace{-0.1em}'}\hspace{-0.4em}.24$ /hour in latitude, + 40 km and 0.29 m/s in distance. +

3. +
The original algorithm is expressed in terms of the obsolete + timescale Ephemeris Time. Either TDB or TT can be used, + but not UT without incurring significant errors ($30\hspace{-0.05em}^{'\hspace{-0.1em}'}$ at + the present time) due to the Moon's + $0\hspace{-0.05em}^{'\hspace{-0.1em}'}\hspace{-0.4em}.5$ /s movement. +
4. +
The algorithm is based on pre IAU 1976 standards. However, + the result has been moved onto the new (FK5) equinox, an + adjustment which is in any case much smaller than the + intrinsic accuracy of the procedure. +
5. +
Velocity is obtained by a complete analytical differentiation + of the Meeus model. +
+

+
REFERENCE: +
Meeus, l'Astronomie, June 1984, p348. +
+
+ +next + +up + +previous +
+ Next: SLA_DMXM - Multiply Matrices +
+Up: SUBPROGRAM SPECIFICATIONS +
+ Previous: SLA_DMAT - Solve Simultaneous Equations +

+

+

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