TCGScale.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,
- * 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.hipparchus.CalculusFieldElement;
- /** Geocentric Coordinate Time.
- * <p>Coordinate time at the center of mass of the Earth.
- * This time scale depends linearly from {@link TTScale Terrestrial 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 TCGScale implements TimeScale {
- /** Serializable UID. */
- private static final long serialVersionUID = 20131209L;
- /** LG rate. */
- private static final double LG_RATE = 6.969290134e-10;
- /** Reference date for TCG.
- * <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;
- /** Offset between TT and TAI scales. */
- private final double ttOffset;
- /**
- * Package private constructor for the factory.
- *
- * @param tt TT time scale.
- * @param tai TAI time scale.
- */
- TCGScale(final TimeScale tt, final TimeScale tai) {
- referenceDate = new AbsoluteDate(1977, 01, 01, tai);
- ttOffset = tt.offsetFromTAI(referenceDate);
- }
- /** {@inheritDoc} */
- @Override
- public double offsetFromTAI(final AbsoluteDate date) {
- return ttOffset + LG_RATE * date.durationFrom(referenceDate);
- }
- /** {@inheritDoc} */
- @Override
- public <T extends CalculusFieldElement<T>> T offsetFromTAI(final FieldAbsoluteDate<T> date) {
- return date.durationFrom(referenceDate).multiply(LG_RATE).add(ttOffset);
- }
- /** {@inheritDoc} */
- public String getName() {
- return "TCG";
- }
- /** {@inheritDoc} */
- public String toString() {
- return getName();
- }
- }