From aef12693c2ec946c5c88070f6707480df7eb26ec Mon Sep 17 00:00:00 2001 From: "David A. Madore" Date: Wed, 18 Apr 2012 19:57:07 +0200 Subject: Add a computation of zonal tide effects on UT1 (from IERS conventions). Plus a Test2 class which tests this on the TAI-UTC difference. --- org/madore/ephem/ZonalTides.java | 57 ++++++++++++++++++++++++++++++++++++++++ 1 file changed, 57 insertions(+) create mode 100644 org/madore/ephem/ZonalTides.java (limited to 'org/madore/ephem/ZonalTides.java') diff --git a/org/madore/ephem/ZonalTides.java b/org/madore/ephem/ZonalTides.java new file mode 100644 index 0000000..166abcc --- /dev/null +++ b/org/madore/ephem/ZonalTides.java @@ -0,0 +1,57 @@ +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 ZonalTides { + + public static enum Variable { + DUT1("dut1"), DLOD("dlod"), DOMEGA("domega"); + 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 + }; + + 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 = ZonalTides.class.getResourceAsStream("zonal-tides.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[5]; + for ( int j=0 ; j<5 ; 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); + } + +} -- cgit v1.2.3