From 221c71e37bdc19dc5bbc1f0303697f67847b7712 Mon Sep 17 00:00:00 2001 From: "David A. Madore" Date: Tue, 27 Mar 2012 19:05:08 +0200 Subject: Nutation. --- org/madore/ephem/Nutation.java | 73 ++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 73 insertions(+) create mode 100644 org/madore/ephem/Nutation.java (limited to 'org/madore/ephem/Nutation.java') diff --git a/org/madore/ephem/Nutation.java b/org/madore/ephem/Nutation.java new file mode 100644 index 0000000..ecc08a4 --- /dev/null +++ b/org/madore/ephem/Nutation.java @@ -0,0 +1,73 @@ +package org.madore.ephem; + +import java.util.List; +import java.util.ArrayList; +import java.util.EnumMap; +import java.io.InputStream; +import java.io.InputStreamReader; +import java.io.BufferedReader; + +public final class Nutation { + + public static enum Variable { + PSI("psi"), EPSILON("epsilon"); + final String name; + Variable(String name) { this.name = name; } + } + + // The argument is in Julian centuries (value is in radians). + public static Comput.Polynomial[] lambdas = new Comput.Polynomial[] { + new Comput.Polynomial(134.96340251*Comput.degree, 1717915923.2178*Comput.arcsecond, 31.8792*Comput.arcsecond +0.051635*Comput.arcsecond, -0.00024470*Comput.arcsecond), // Delaunay l + new Comput.Polynomial(357.52910918*Comput.degree, 129596581.0481*Comput.arcsecond, -0.5532*Comput.arcsecond +0.000136*Comput.arcsecond, -0.00001149*Comput.arcsecond), // Delaunay l′ + new Comput.Polynomial(93.27209062*Comput.degree, 1739527262.8478*Comput.arcsecond, -12.7512*Comput.arcsecond -0.001037*Comput.arcsecond, 0.00000417*Comput.arcsecond), // Delaunay F + new Comput.Polynomial(297.85019547*Comput.degree, 1602961601.2090*Comput.arcsecond, -6.3706*Comput.arcsecond +0.006593*Comput.arcsecond, -0.00003169*Comput.arcsecond), // Delaunay D + new Comput.Polynomial(125.04455501*Comput.degree, -6962890.5431*Comput.arcsecond, 7.4722*Comput.arcsecond +0.007702*Comput.arcsecond, -0.00005939*Comput.arcsecond), // Delaunay Ω + new Comput.Polynomial(4.402608842, 2608.7903141574), // L(Mercury) + new Comput.Polynomial(3.176146697, 1021.3285546211), // L(Venus) + new Comput.Polynomial(1.753470314, 628.3075849991), // L(Earth) + new Comput.Polynomial(6.203480913, 334.0612426700), // L(Mars) + new Comput.Polynomial(0.599546497, 52.9690962641), // L(Jupiter) + new Comput.Polynomial(0.874016757, 21.3299104960), // L(Saturn) + new Comput.Polynomial(5.481293872, 7.4781598567), // L(Uranus) + new Comput.Polynomial(5.311886287, 3.8133035638), // L(Neptune) + new Comput.Polynomial(0, 0.02438175, 0.00000538691) // General precession + }; + + private static EnumMap data = new EnumMap(Variable.class); + + public static Comput.SumPoisson2Terms getFunc(Variable v) { + if ( ! data.containsKey(v) ) { + List series = new ArrayList(); + try { + InputStream str = Nutation.class.getResourceAsStream("nutation.dat"); + BufferedReader in = new BufferedReader(new InputStreamReader(str, "utf-8")); + String s; + while ( ( s = in.readLine() ) != null ) { + String[] fields = s.split("\t"); + if ( ! fields[1].equals(v.name) ) + continue; + int deg = Integer.parseInt(fields[2]); + String[] subfields = fields[3].split(","); + double[] om = new double[14]; + for ( int j=0 ; j<14 ; j++ ) + om[j] = Double.parseDouble(subfields[j]); + double b = Double.parseDouble(fields[4]); + double a = Double.parseDouble(fields[5]); + series.add(Comput.Poisson2Term.ab(deg, a, b, om, lambdas)); + } + } catch ( Exception e ) { + throw new RuntimeException(e); + } + data.put(v, new Comput.SumPoisson2Terms(series)); + } + return data.get(v); + } + + public static Frames.RotationMatrix matrix(double t) { + Frames.RotationMatrix mat1 = Frames.RotationMatrix.rotx(Precession.epsilon.v(t)*Comput.arcsecond); + Frames.RotationMatrix mat2 = Frames.RotationMatrix.rotz(-getFunc(Variable.PSI).v(t)*Comput.arcsecond).apply(mat1); + Frames.RotationMatrix mat3 = Frames.RotationMatrix.rotx(-(Precession.epsilon.v(t)+getFunc(Variable.EPSILON).v(t))*Comput.arcsecond).apply(mat2); + return mat3; + } + +} -- cgit v1.2.3