TCBScale.java
/* Copyright 2002-2022 CS GROUP
* Licensed to CS GROUP (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,
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* See the License for the specific language governing permissions and
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*/
package org.orekit.time;
import org.hipparchus.CalculusFieldElement;
/** Barycentric Coordinate Time.
* <p>Coordinate time at the center of mass of the Solar System.
* This time scale depends linearly from {@link TDBScale Barycentric Dynamical Time}.</p>
* <p>This is intended to be accessed thanks to {@link TimeScales},
* so there is no public constructor.</p>
* @author Luc Maisonobe
* @see AbsoluteDate
*/
public class TCBScale implements TimeScale {
/** Serializable UID. */
private static final long serialVersionUID = 20131209L;
/** LG rate. */
private static final double LB_RATE = 1.550519768e-8;
/** Reference date for TCB.
* <p>The reference date is such that the four following instants are equal:</p>
* <ul>
* <li>1977-01-01T00:00:32.184 TT</li>
* <li>1977-01-01T00:00:32.184 TCG</li>
* <li>1977-01-01T00:00:32.184 TCB</li>
* <li>1977-01-01T00:00:00.000 TAI</li>
* </ul>
*/
private final AbsoluteDate referenceDate;
/** Barycentric dynamic time scale. */
private final TDBScale tdb;
/**
* Package private constructor for the factory.
*
* @param tdb Barycentric dynamic time scale
* @param tai TAI time scale.
*/
TCBScale(final TDBScale tdb, final TimeScale tai) {
this.tdb = tdb;
referenceDate = new AbsoluteDate(1977, 01, 01, tai);
}
/** {@inheritDoc} */
@Override
public double offsetFromTAI(final AbsoluteDate date) {
return tdb.offsetFromTAI(date) + LB_RATE * date.durationFrom(referenceDate);
}
/** {@inheritDoc} */
@Override
public <T extends CalculusFieldElement<T>> T offsetFromTAI(final FieldAbsoluteDate<T> date) {
return tdb.offsetFromTAI(date).add(date.durationFrom(referenceDate).multiply(LB_RATE));
}
/** {@inheritDoc} */
public String getName() {
return "TCB";
}
/** {@inheritDoc} */
public String toString() {
return getName();
}
}