/* Copyright 2002-2017 CS Systèmes d'Information
* Licensed to CS Systèmes d'Information (CS) under one or more
* contributor license agreements. See the NOTICE file distributed with
* this work for additional information regarding copyright ownership.
* CS licenses this file to You under the Apache License, Version 2.0
* (the "License"); you may not use this file except in compliance with
* the License. You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package org.orekit.time;
import org.junit.Assert;
import org.junit.Before;
import org.junit.Test;
import org.orekit.Utils;
import org.orekit.errors.OrekitException;
import org.orekit.utils.IERSConventions;
public class TDBScaleTest {
@Test
public void testReference() {
TimeScale scale = TimeScalesFactory.getTDB();
Assert.assertEquals("TDB", scale.toString());
Assert.assertEquals(32.183927340791372839, scale.offsetFromTAI(AbsoluteDate.J2000_EPOCH), 1.0e-15);
}
@Test
public void testDate5000000() {
TimeScale scale = TimeScalesFactory.getTDB();
AbsoluteDate date = AbsoluteDate.J2000_EPOCH.shiftedBy(5000000);
Assert.assertEquals(32.185364155950634549, scale.offsetFromTAI(date), 1.0e-13);
}
@Test
public void testToTAI5000000() {
TimeScale scale = TimeScalesFactory.getTDB();
AbsoluteDate date = new AbsoluteDate(2000, 2, 28, 8, 53, 20.001364155950634549, scale);
double dt = AbsoluteDate.J2000_EPOCH.shiftedBy(5000000).durationFrom(date);
Assert.assertEquals(0.0, dt, 1.0e-13);
}
@Test
public void testToTAI() {
TimeScale scale = TimeScalesFactory.getTDB();
AbsoluteDate date = new AbsoluteDate(2000, 01, 01, 11, 59, 59.999927340791372839, scale);
double dt = AbsoluteDate.J2000_EPOCH.durationFrom(date);
Assert.assertEquals(0.0, dt, 1.0e-13);
}
@Test
public void testSofa() {
// the reference data for this test was obtained by running the following program
// with version 2012-03-01 of the SOFA library in C
// double tai1, tai2, tttdb;
//
// tai1 = 2448939.5;
// tai2 = 0.123;
// tttdb = iauDtdb(tai1, tai2, 0.0, 0.0, 0.0, 0.0);
//
// printf("iauDtdb(%.20g, %.20g, 0.0, 0.0, 0.0, 0.0)\n --> %.20g\n", tai1, tai2, tttdb);
// which displays the following result:
// iauDtdb(2448939.5, 0.12299999999999999822, 0.0, 0.0, 0.0, 0.0)
// --> -0.001279984433218163669
// the difference with SOFA is quite big (10 microseconds) because SOFA uses
// the full Fairhead & Bretagnon model from 1990, including planetary effects,
// whereas in Orekit we use only the conventional definition from IAU general
// assembly 2006. So this difference is expected
AbsoluteDate date = new AbsoluteDate(1992, 11, 13, 2, 57, 7.2,
TimeScalesFactory.getTAI());
double delta = TimeScalesFactory.getTDB().offsetFromTAI(date) -
TimeScalesFactory.getTT().offsetFromTAI(date);
Assert.assertEquals(-0.001279984433218163669, delta, 1.0e-5);
}
@Test
public void testAAS06134() throws OrekitException {
// this reference test has been extracted from the following paper:
// Implementation Issues Surrounding the New IAU Reference Systems for Astrodynamics
// David A. Vallado, John H. Seago, P. Kenneth Seidelmann
// http://www.centerforspace.com/downloads/files/pubs/AAS-06-134.pdf
// Note that the dUT1 here is -0.439962, whereas it is -0.4399619 in the book
Utils.setLoaders(IERSConventions.IERS_1996,
Utils.buildEOPList(IERSConventions.IERS_1996, new double[][] {
{ 53098, -0.439962, 0.0015563, -0.140682, 0.333309, -0.052195, -0.003875, Double.NaN, Double.NaN },
{ 53099, -0.439962, 0.0015563, -0.140682, 0.333309, -0.052195, -0.003875, Double.NaN, Double.NaN },
{ 53100, -0.439962, 0.0015563, -0.140682, 0.333309, -0.052195, -0.003875, Double.NaN, Double.NaN },
{ 53101, -0.439962, 0.0015563, -0.140682, 0.333309, -0.052195, -0.003875, Double.NaN, Double.NaN },
{ 53102, -0.439962, 0.0015563, -0.140682, 0.333309, -0.052195, -0.003875, Double.NaN, Double.NaN },
{ 53103, -0.439962, 0.0015563, -0.140682, 0.333309, -0.052195, -0.003875, Double.NaN, Double.NaN },
{ 53104, -0.439962, 0.0015563, -0.140682, 0.333309, -0.052195, -0.003875, Double.NaN, Double.NaN },
{ 53105, -0.439962, 0.0015563, -0.140682, 0.333309, -0.052195, -0.003875, Double.NaN, Double.NaN }
}));
AbsoluteDate date =
new AbsoluteDate(2004, 4, 6, 7, 51, 28.386009, TimeScalesFactory.getUTC());
DateTimeComponents components = date.getComponents(TimeScalesFactory.getTDB());
Assert.assertEquals(2004, components.getDate().getYear());
Assert.assertEquals( 4, components.getDate().getMonth());
Assert.assertEquals( 6, components.getDate().getDay());
Assert.assertEquals( 7, components.getTime().getHour());
Assert.assertEquals( 52, components.getTime().getMinute());
// the "large" threshold in this test is due to the fact TDB model is
// approximated both in Orekit and in the reference paper. the difference
// is however small as the model in the paper is announced as being accurate
// to 50 micro seconds, and the test here is far below this value
Assert.assertEquals( 32.5716651154, components.getTime().getSecond(), 1.4e-8);
}
@Test
public void testDuringLeap() throws OrekitException {
final TimeScale utc = TimeScalesFactory.getUTC();
final TimeScale scale = TimeScalesFactory.getTDB();
final AbsoluteDate before = new AbsoluteDate(new DateComponents(1983, 06, 30),
new TimeComponents(23, 59, 59),
utc);
final AbsoluteDate during = before.shiftedBy(1.25);
Assert.assertEquals(61, utc.minuteDuration(during));
Assert.assertEquals(1.0, utc.getLeap(during), 1.0e-10);
Assert.assertEquals(60, scale.minuteDuration(during));
Assert.assertEquals(0.0, scale.getLeap(during), 1.0e-10);
}
@Before
public void setUp() throws OrekitException {
Utils.setDataRoot("regular-data");
}
}