TimeScales.java

  1. /* Contributed in the public domain.
  2.  * Licensed to CS GROUP (CS) under one or more
  3.  * contributor license agreements.  See the NOTICE file distributed with
  4.  * this work for additional information regarding copyright ownership.
  5.  * CS licenses this file to You under the Apache License, Version 2.0
  6.  * (the "License"); you may not use this file except in compliance with
  7.  * the License.  You may obtain a copy of the License at
  8.  *
  9.  *   http://www.apache.org/licenses/LICENSE-2.0
  10.  *
  11.  * Unless required by applicable law or agreed to in writing, software
  12.  * distributed under the License is distributed on an "AS IS" BASIS,
  13.  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
  14.  * See the License for the specific language governing permissions and
  15.  * limitations under the License.
  16.  */
  17. package org.orekit.time;

  19. import java.util.Collection;
  20. import java.util.function.BiFunction;

  22. import org.orekit.frames.EOPEntry;
  23. import org.orekit.frames.Frames;
  24. import org.orekit.utils.IERSConventions;

  26. /**
  27.  * A collection of {@link TimeScale}s. This interface defines methods for obtaining
  28.  * instances of many common time scales.
  29.  *
  30.  * @author Luc Maisonobe
  31.  * @author Evan Ward
  32.  * @see TimeScalesFactory
  33.  * @see TimeScale
  34.  * @see LazyLoadedTimeScales
  35.  * @see #of(Collection, BiFunction)
  36.  * @since 10.1
  37.  */
  38. public interface TimeScales {

  40.     /**
  41.      * Get the International Atomic Time scale.
  42.      *
  43.      * @return International Atomic Time scale
  44.      */
  45.     TAIScale getTAI();

  47.     /**
  48.      * Get the Universal Time Coordinate scale.
  49.      *
  50.      * @return Universal Time Coordinate scale
  51.      */
  52.     UTCScale getUTC();

  54.     /**
  55.      * Get the Universal Time 1 scale.
  56.      *
  57.      * @param conventions IERS conventions for which EOP parameters will provide dUT1
  58.      * @param simpleEOP   if true, tidal effects are ignored when interpolating EOP
  59.      * @return Universal Time 1 scale
  60.      * @see #getUTC()
  61.      * @see Frames#getEOPHistory(IERSConventions, boolean)
  62.      */
  63.     UT1Scale getUT1(IERSConventions conventions, boolean simpleEOP);

  65.     /**
  66.      * Get the Terrestrial Time scale.
  67.      *
  68.      * @return Terrestrial Time scale
  69.      */
  70.     TTScale getTT();

  72.     /**
  73.      * Get the Galileo System Time scale.
  74.      *
  75.      * @return Galileo System Time scale
  76.      */
  77.     GalileoScale getGST();

  79.     /**
  80.      * Get the GLObal NAvigation Satellite System time scale.
  81.      *
  82.      * @return GLObal NAvigation Satellite System time scale
  83.      */
  84.     GLONASSScale getGLONASS();

  86.     /**
  87.      * Get the Quasi-Zenith Satellite System time scale.
  88.      *
  89.      * @return Quasi-Zenith Satellite System time scale
  90.      */
  91.     QZSSScale getQZSS();

  93.     /**
  94.      * Get the Global Positioning System scale.
  95.      *
  96.      * @return Global Positioning System scale
  97.      */
  98.     GPSScale getGPS();

  100.     /**
  101.      * Get the Geocentric Coordinate Time scale.
  102.      *
  103.      * @return Geocentric Coordinate Time scale
  104.      */
  105.     TCGScale getTCG();

  107.     /**
  108.      * Get the Barycentric Dynamic Time scale.
  109.      *
  110.      * @return Barycentric Dynamic Time scale
  111.      */
  112.     TDBScale getTDB();

  114.     /**
  115.      * Get the Barycentric Coordinate Time scale.
  116.      *
  117.      * @return Barycentric Coordinate Time scale
  118.      */
  119.     TCBScale getTCB();

  121.     /**
  122.      * Get the Greenwich Mean Sidereal Time scale.
  123.      *
  124.      * @param conventions IERS conventions for which EOP parameters will provide dUT1
  125.      * @param simpleEOP   if true, tidal effects are ignored when interpolating EOP
  126.      * @return Greenwich Mean Sidereal Time scale
  127.      * @since 7.0
  128.      */
  129.     GMSTScale getGMST(IERSConventions conventions, boolean simpleEOP);

  131.     /**
  132.      * Get the Navigation with Indian Constellation time scale.
  133.      *
  134.      * @return Navigation with Indian Constellation time scale
  135.      */
  136.     NavicScale getNavIC();

  138.     /**
  139.      * Get the BeiDou Navigation Satellite System time scale.
  140.      *
  141.      * @return BeiDou Navigation Satellite System time scale
  142.      */
  143.     BDTScale getBDT();

  145.     /**
  146.      * Reference epoch for julian dates: -4712-01-01T12:00:00 Terrestrial Time.
  147.      * <p>Both <code>java.util.Date</code> and {@link DateComponents} classes
  148.      * follow the astronomical conventions and consider a year 0 between years -1 and +1,
  149.      * hence this reference date lies in year -4712 and not in year -4713 as can be seen
  150.      * in other documents or programs that obey a different convention (for example the
  151.      * <code>convcal</code> utility).</p>
  152.      *
  153.      * @return Julian epoch.
  154.      */
  155.     AbsoluteDate getJulianEpoch();

  157.     /**
  158.      * Reference epoch for modified julian dates: 1858-11-17T00:00:00 Terrestrial Time.
  159.      *
  160.      * @return Modified Julian Epoch
  161.      */
  162.     AbsoluteDate getModifiedJulianEpoch();

  164.     /**
  165.      * Reference epoch for 1950 dates: 1950-01-01T00:00:00 Terrestrial Time.
  166.      *
  167.      * @return Fifties Epoch
  168.      */
  169.     AbsoluteDate getFiftiesEpoch();

  171.     /**
  172.      * Reference epoch for CCSDS Time Code Format (CCSDS 301.0-B-4): 1958-01-01T00:00:00
  173.      * International Atomic Time (<em>not</em> UTC).
  174.      *
  175.      * @return CCSDS Epoch
  176.      */
  177.     AbsoluteDate getCcsdsEpoch();

  179.     /**
  180.      * Reference epoch for Galileo System Time: 1999-08-22T00:00:00 GST.
  181.      *
  182.      * @return Galileo Epoch
  183.      */
  184.     AbsoluteDate getGalileoEpoch();

  186.     /**
  187.      * Reference epoch for GPS weeks: 1980-01-06T00:00:00 GPS time.
  188.      *
  189.      * @return GPS Epoch
  190.      */
  191.     AbsoluteDate getGpsEpoch();

  193.     /**
  194.      * Reference epoch for QZSS weeks: 1980-01-06T00:00:00 QZSS time.
  195.      *
  196.      * @return QZSS Epoch
  197.      */
  198.     AbsoluteDate getQzssEpoch();

  200.     /**
  201.      * Reference epoch for NavIC weeks: 1999-08-22T00:00:00 NavIC time.
  202.      *
  203.      * @return NavIC Epoch
  204.      */
  205.     AbsoluteDate getNavicEpoch();

  207.     /**
  208.      * Reference epoch for BeiDou weeks: 2006-01-01T00:00:00 UTC.
  209.      *
  210.      * @return Beidou Epoch
  211.      */
  212.     AbsoluteDate getBeidouEpoch();

  214.     /**
  215.      * Reference epoch for GLONASS four-year interval number: 1996-01-01T00:00:00 GLONASS
  216.      * time.
  217.      * <p>By convention, TGLONASS = UTC + 3 hours.</p>
  218.      *
  219.      * @return GLONASS Epoch
  220.      */
  221.     AbsoluteDate getGlonassEpoch();

  223.     /**
  224.      * J2000.0 Reference epoch: 2000-01-01T12:00:00 Terrestrial Time (<em>not</em> UTC).
  225.      *
  226.      * @return J2000 Epoch
  227.      * @see AbsoluteDate#createJulianEpoch(double)
  228.      * @see AbsoluteDate#createBesselianEpoch(double)
  229.      */
  230.     AbsoluteDate getJ2000Epoch();

  232.     /**
  233.      * Java Reference epoch: 1970-01-01T00:00:00 Universal Time Coordinate.
  234.      * <p>
  235.      * Between 1968-02-01 and 1972-01-01, UTC-TAI = 4.213 170 0s + (MJD - 39 126) x 0.002
  236.      * 592s. As on 1970-01-01 MJD = 40587, UTC-TAI = 8.000082s
  237.      * </p>
  238.      *
  239.      * @return Java Epoch
  240.      */
  241.     AbsoluteDate getJavaEpoch();

  243.     /**
  244.      * Dummy date at infinity in the past direction.
  245.      *
  246.      * @return the earliest date.
  247.      */
  248.     AbsoluteDate getPastInfinity();

  250.     /**
  251.      * Dummy date at infinity in the future direction.
  252.      *
  253.      * @return the latest date.
  254.      */
  255.     AbsoluteDate getFutureInfinity();

  257.     /**
  258.      * Build an instance corresponding to a Julian Epoch (JE).
  259.      * <p>According to Lieske paper: <a
  260.      * href="http://articles.adsabs.harvard.edu/cgi-bin/nph-iarticle_query?1979A%26A....73..282L&amp;defaultprint=YES&amp;filetype=.pdf.">
  261.      * Precession Matrix Based on IAU (1976) System of Astronomical Constants</a>,
  262.      * Astronomy and Astrophysics, vol. 73, no. 3, Mar. 1979, p. 282-284, Julian Epoch is
  263.      * related to Julian Ephemeris Date as:</p>
  264.      * <pre>
  265.      * JE = 2000.0 + (JED - 2451545.0) / 365.25
  266.      * </pre>
  267.      * <p>
  268.      * This method reverts the formula above and computes an {@code AbsoluteDate} from the
  269.      * Julian Epoch.
  270.      * </p>
  271.      *
  272.      * @param julianEpoch Julian epoch, like 2000.0 for defining the classical reference
  273.      *                    J2000.0
  274.      * @return a new instant
  275.      * @see #getJ2000Epoch()
  276.      * @see #createBesselianEpoch(double)
  277.      */
  278.     AbsoluteDate createJulianEpoch(double julianEpoch);

  280.     /**
  281.      * Build an instance corresponding to a Besselian Epoch (BE).
  282.      * <p>According to Lieske paper: <a
  283.      * href="http://articles.adsabs.harvard.edu/cgi-bin/nph-iarticle_query?1979A%26A....73..282L&amp;defaultprint=YES&amp;filetype=.pdf.">
  284.      * Precession Matrix Based on IAU (1976) System of Astronomical Constants</a>,
  285.      * Astronomy and Astrophysics, vol. 73, no. 3, Mar. 1979, p. 282-284, Besselian Epoch
  286.      * is related to Julian Ephemeris Date as:</p>
  287.      * <pre>
  288.      * BE = 1900.0 + (JED - 2415020.31352) / 365.242198781
  289.      * </pre>
  290.      * <p>
  291.      * This method reverts the formula above and computes an {@code AbsoluteDate} from the
  292.      * Besselian Epoch.
  293.      * </p>
  294.      *
  295.      * @param besselianEpoch Besselian epoch, like 1950 for defining the classical
  296.      *                       reference B1950.0
  297.      * @return a new instant
  298.      * @see #createJulianEpoch(double)
  299.      */
  300.     AbsoluteDate createBesselianEpoch(double besselianEpoch);

  302.     /* Helpers for creating new instances. */

  304.     /**
  305.      * Create a set of time scales where all the data is loaded from the given functions.
  306.      *
  307.      * @param utcMinusTai offsets used to compute UTC. If the pre-1972 linear offsets are
  308.      *                    missing they will be added.
  309.      * @param eopSupplier function to retrieve the EOP data. Since the EOP have to be
  310.      *                    reloaded every time a different {@link IERSConventions} is
  311.      *                    requested this function may be called multiple times. The
  312.      *                    requested conventions and the created time scales are passed as
  313.      *                    arguments. Attempting to call {@link #getUT1(IERSConventions,
  314.      *                    boolean)} or {@link #getGMST(IERSConventions, boolean)} on the
  315.      *                    time scales argument may result in unbounded recursion. To
  316.      *                    ignore EOP corrections this function should return an empty
  317.      *                    collection.
  318.      * @return a set of time scales based on the given data.
  319.      * @see UTCTAIOffsetsLoader.Parser
  320.      * @see org.orekit.frames.EopHistoryLoader.Parser
  321.      */
  322.     static TimeScales of(
  323.             final Collection<? extends OffsetModel> utcMinusTai,
  324.             final BiFunction<
  325.                     ? super IERSConventions,
  326.                     ? super TimeScales,
  327.                     ? extends Collection<? extends EOPEntry>> eopSupplier) {
  328.         return new PreloadedTimeScales(utcMinusTai, eopSupplier);
  329.     }

  331. }
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