UT1Scale.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;
import org.orekit.frames.EOPHistory;
/** Universal Time 1.
* <p>UT1 is a time scale directly linked to the actual rotation of the Earth.
* It is an irregular scale, reflecting Earth irregular rotation rate. The offset
* between UT1 and {@link UTCScale UTC} is found in the Earth Orientation
* Parameters published by IERS.</p>
* @author Luc Maisonobe
* @see AbsoluteDate
* @since 5.1
*/
public class UT1Scale implements TimeScale {
/** Serializable UID. */
private static final long serialVersionUID = 20131209L;
/** UTC scale. */
private final UTCScale utc;
/** EOP history. */
private final EOPHistory eopHistory;
/** Simple constructor.
* @param eopHistory user supplied EOP history (may be null)
* @param utc UTC time scale
*/
protected UT1Scale(final EOPHistory eopHistory, final UTCScale utc) {
this.eopHistory = eopHistory;
this.utc = utc;
}
/** Get the associated UTC scale.
* @return associated UTC scale.
* @since 9.1
*/
public UTCScale getUTCScale() {
return utc;
}
/** Get the EOP history.
* @return eop history (may be null)
*/
public EOPHistory getEOPHistory() {
return eopHistory;
}
/** {@inheritDoc} */
@Override
public double offsetFromTAI(final AbsoluteDate date) {
final double dtu1 = eopHistory == null ? 0 : eopHistory.getUT1MinusUTC(date);
final double utcMinusTai = utc.offsetFromTAI(date);
return utcMinusTai + dtu1;
}
/** {@inheritDoc} */
@Override
public <T extends CalculusFieldElement<T>> T offsetFromTAI(final FieldAbsoluteDate<T> date) {
final T dtu1 = eopHistory == null ? date.getField().getZero() : eopHistory.getUT1MinusUTC(date);
final T utcMinusTai = utc.offsetFromTAI(date);
return utcMinusTai.add(dtu1);
}
/** {@inheritDoc} */
public String getName() {
return "UT1";
}
/** {@inheritDoc} */
public String toString() {
return getName();
}
}