Keep an copy CalendarAstronomer of in android_icu4j/src/icu74

In the ICU4J 75, due to ICU-22698, dead code is removed from
CalendarAstronomer. However, it's still used by system server and
and Wallpaper app. We keep a copy from ICU 74.

Test: m droid
Change-Id: I982ba9bc070ed3f1075e8ec680d1b2ddca4f81dc

3 files changed, 1720 insertions, 15 deletions

diff --git a/android_icu4j/src/icu74/Android.bp b/android_icu4j/src/icu74/Android.bp
new file mode 100644
index 000000000..e9085323e
--- /dev/null
+++ b/android_icu4j/src/icu74/Android.bp
@@ -0,0 +1,46 @@
+//
+// Copyright (C) 2024 The Android Open Source Project
+//
+// Licensed 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 {
+    default_team: "trendy_team_java_core_libraries",
+    default_visibility: ["//visibility:private"],
+    // See: http://go/android-license-faq
+    // A large-scale-change added 'default_applicable_licenses' to import
+    // all of the 'license_kinds' from "external_icu_license"
+    // to get the below license kinds:
+    //   SPDX-license-identifier-Apache-2.0
+    //   SPDX-license-identifier-BSD
+    //   SPDX-license-identifier-ICU
+    //   SPDX-license-identifier-MIT
+    //   SPDX-license-identifier-Unicode-DFS
+    //   legacy_unencumbered
+    default_applicable_licenses: ["external_icu_license"],
+}
+
+// Small static library used by TwilightService in the system server and WallpaperPicker2 app. To
+// avoid @CorePlaformApi, the system server doesn't use CalendarAstronomer in android.icu.
+// Don't link this in boot classpath or Zygote to avoid class collision with the
+// com.ibm.icu.impl.CalendarAstronomer in the app classloader.
+java_library_static {
+    name: "icu4j_calendar_astronomer",
+    host_supported: false,
+    sdk_version: "core_current",
+    srcs: ["main/java/com/ibm/icu/impl/CalendarAstronomer.java"],
+    visibility: [
+        "//frameworks/base/services/core",
+        "//packages/apps/WallpaperPicker2",
+    ],
+}
diff --git a/android_icu4j/src/icu74/main/java/com/ibm/icu/impl/CalendarAstronomer.java b/android_icu4j/src/icu74/main/java/com/ibm/icu/impl/CalendarAstronomer.java
new file mode 100644
index 000000000..1aaaf2b47
--- /dev/null
+++ b/android_icu4j/src/icu74/main/java/com/ibm/icu/impl/CalendarAstronomer.java
@@ -0,0 +1,1674 @@
+// © 2016 and later: Unicode, Inc. and others.
+// License & terms of use: http://www.unicode.org/copyright.html
+/*
+ *******************************************************************************
+ * Copyright (C) 1996-2011, International Business Machines Corporation and    *
+ * others. All Rights Reserved.                                                *
+ *******************************************************************************
+ */
+
+package com.ibm.icu.impl;
+
+import java.util.Date;
+import java.util.TimeZone;
+
+/**
+ * <code>CalendarAstronomer</code> is a class that can perform the calculations to
+ * determine the positions of the sun and moon, the time of sunrise and
+ * sunset, and other astronomy-related data.  The calculations it performs
+ * are in some cases quite complicated, and this utility class saves you
+ * the trouble of worrying about them.
+ * <p>
+ * The measurement of time is a very important part of astronomy.  Because
+ * astronomical bodies are constantly in motion, observations are only valid
+ * at a given moment in time.  Accordingly, each <code>CalendarAstronomer</code>
+ * object has a <code>time</code> property that determines the date
+ * and time for which its calculations are performed.  You can set and
+ * retrieve this property with {@link #setDate setDate}, {@link #getDate getDate}
+ * and related methods.
+ * <p>
+ * Almost all of the calculations performed by this class, or by any
+ * astronomer, are approximations to various degrees of accuracy.  The
+ * calculations in this class are mostly modelled after those described
+ * in the book
+ * <a href="http://www.amazon.com/exec/obidos/ISBN=0521356997" target="_top">
+ * Practical Astronomy With Your Calculator</a>, by Peter J.
+ * Duffett-Smith, Cambridge University Press, 1990.  This is an excellent
+ * book, and if you want a greater understanding of how these calculations
+ * are performed it a very good, readable starting point.
+ * <p>
+ * <strong>WARNING:</strong> This class is very early in its development, and
+ * it is highly likely that its API will change to some degree in the future.
+ * At the moment, it basically does just enough to support {@link com.ibm.icu.util.IslamicCalendar}
+ * and {@link com.ibm.icu.util.ChineseCalendar}.
+ *
+ * @author Laura Werner
+ * @author Alan Liu
+ * @internal
+ */
+public class CalendarAstronomer {
+
+    //-------------------------------------------------------------------------
+    // Astronomical constants
+    //-------------------------------------------------------------------------
+
+    /**
+     * The number of standard hours in one sidereal day.
+     * Approximately 24.93.
+     * @internal
+     */
+    public static final double SIDEREAL_DAY = 23.93446960027;
+
+    /**
+     * The number of sidereal hours in one mean solar day.
+     * Approximately 24.07.
+     * @internal
+     */
+    public static final double SOLAR_DAY =  24.065709816;
+
+    /**
+     * The average number of solar days from one new moon to the next.  This is the time
+     * it takes for the moon to return the same ecliptic longitude as the sun.
+     * It is longer than the sidereal month because the sun's longitude increases
+     * during the year due to the revolution of the earth around the sun.
+     * Approximately 29.53.
+     *
+     * @see #SIDEREAL_MONTH
+     * @internal
+     */
+    public static final double SYNODIC_MONTH = 29.530588853;
+
+    /**
+     * The average number of days it takes
+     * for the moon to return to the same ecliptic longitude relative to the
+     * stellar background.  This is referred to as the sidereal month.
+     * It is shorter than the synodic month due to
+     * the revolution of the earth around the sun.
+     * Approximately 27.32.
+     *
+     * @see #SYNODIC_MONTH
+     * @internal
+     */
+    public static final double SIDEREAL_MONTH = 27.32166;
+
+    /**
+     * The average number number of days between successive vernal equinoxes.
+     * Due to the precession of the earth's
+     * axis, this is not precisely the same as the sidereal year.
+     * Approximately 365.24
+     *
+     * @see #SIDEREAL_YEAR
+     * @internal
+     */
+    public static final double TROPICAL_YEAR = 365.242191;
+
+    /**
+     * The average number of days it takes
+     * for the sun to return to the same position against the fixed stellar
+     * background.  This is the duration of one orbit of the earth about the sun
+     * as it would appear to an outside observer.
+     * Due to the precession of the earth's
+     * axis, this is not precisely the same as the tropical year.
+     * Approximately 365.25.
+     *
+     * @see #TROPICAL_YEAR
+     * @internal
+     */
+    public static final double SIDEREAL_YEAR = 365.25636;
+
+    //-------------------------------------------------------------------------
+    // Time-related constants
+    //-------------------------------------------------------------------------
+
+    /**
+     * The number of milliseconds in one second.
+     * @internal
+     */
+    public static final int  SECOND_MS = 1000;
+
+    /**
+     * The number of milliseconds in one minute.
+     * @internal
+     */
+    public static final int  MINUTE_MS = 60*SECOND_MS;
+
+    /**
+     * The number of milliseconds in one hour.
+     * @internal
+     */
+    public static final int  HOUR_MS   = 60*MINUTE_MS;
+
+    /**
+     * The number of milliseconds in one day.
+     * @internal
+     */
+    public static final long DAY_MS    = 24*HOUR_MS;
+
+    /**
+     * The start of the julian day numbering scheme used by astronomers, which
+     * is 1/1/4713 BC (Julian), 12:00 GMT.  This is given as the number of milliseconds
+     * since 1/1/1970 AD (Gregorian), a negative number.
+     * Note that julian day numbers and
+     * the Julian calendar are <em>not</em> the same thing.  Also note that
+     * julian days start at <em>noon</em>, not midnight.
+     * @internal
+     */
+    public static final long JULIAN_EPOCH_MS = -210866760000000L;
+
+//  static {
+//      Calendar cal = new GregorianCalendar(TimeZone.getTimeZone("GMT"));
+//      cal.clear();
+//      cal.set(cal.ERA, 0);
+//      cal.set(cal.YEAR, 4713);
+//      cal.set(cal.MONTH, cal.JANUARY);
+//      cal.set(cal.DATE, 1);
+//      cal.set(cal.HOUR_OF_DAY, 12);
+//      System.out.println("1.5 Jan 4713 BC = " + cal.getTime().getTime());
+
+//      cal.clear();
+//      cal.set(cal.YEAR, 2000);
+//      cal.set(cal.MONTH, cal.JANUARY);
+//      cal.set(cal.DATE, 1);
+//      cal.add(cal.DATE, -1);
+//      System.out.println("0.0 Jan 2000 = " + cal.getTime().getTime());
+//  }
+
+    /**
+     * Milliseconds value for 0.0 January 2000 AD.
+     */
+    static final long EPOCH_2000_MS = 946598400000L;
+
+    //-------------------------------------------------------------------------
+    // Assorted private data used for conversions
+    //-------------------------------------------------------------------------
+
+    // My own copies of these so compilers are more likely to optimize them away
+    static private final double PI = 3.14159265358979323846;
+    static private final double PI2 = PI * 2.0;
+
+    static private final double RAD_HOUR = 12 / PI;        // radians -> hours
+    static private final double DEG_RAD  = PI / 180;        // degrees -> radians
+    static private final double RAD_DEG  = 180 / PI;        // radians -> degrees
+
+    //-------------------------------------------------------------------------
+    // Constructors
+    //-------------------------------------------------------------------------
+
+    /**
+     * Construct a new <code>CalendarAstronomer</code> object that is initialized to
+     * the current date and time.
+     * @internal
+     */
+    public CalendarAstronomer() {
+        this(System.currentTimeMillis());
+    }
+
+    /**
+     * Construct a new <code>CalendarAstronomer</code> object that is initialized to
+     * the specified date and time.
+     * @internal
+     */
+    public CalendarAstronomer(Date d) {
+        this(d.getTime());
+    }
+
+    /**
+     * Construct a new <code>CalendarAstronomer</code> object that is initialized to
+     * the specified time.  The time is expressed as a number of milliseconds since
+     * January 1, 1970 AD (Gregorian).
+     *
+     * @see java.util.Date#getTime()
+     * @internal
+     */
+    public CalendarAstronomer(long aTime) {
+        time = aTime;
+    }
+
+    /**
+     * Construct a new <code>CalendarAstronomer</code> object with the given
+     * latitude and longitude.  The object's time is set to the current
+     * date and time.
+     * <p>
+     * @param longitude The desired longitude, in <em>degrees</em> east of
+     *                  the Greenwich meridian.
+     *
+     * @param latitude  The desired latitude, in <em>degrees</em>.  Positive
+     *                  values signify North, negative South.
+     *
+     * @see java.util.Date#getTime()
+     * @internal
+     */
+    public CalendarAstronomer(double longitude, double latitude) {
+        this();
+        fLongitude = normPI(longitude * DEG_RAD);
+        fLatitude  = normPI(latitude  * DEG_RAD);
+        fGmtOffset = (long)(fLongitude * 24 * HOUR_MS / PI2);
+    }
+
+
+    //-------------------------------------------------------------------------
+    // Time and date getters and setters
+    //-------------------------------------------------------------------------
+
+    /**
+     * Set the current date and time of this <code>CalendarAstronomer</code> object.  All
+     * astronomical calculations are performed based on this time setting.
+     *
+     * @param aTime the date and time, expressed as the number of milliseconds since
+     *              1/1/1970 0:00 GMT (Gregorian).
+     *
+     * @see #setDate
+     * @see #getTime
+     * @internal
+     */
+    public void setTime(long aTime) {
+        time = aTime;
+        clearCache();
+    }
+
+    /**
+     * Set the current date and time of this <code>CalendarAstronomer</code> object.  All
+     * astronomical calculations are performed based on this time setting.
+     *
+     * @param date the time and date, expressed as a <code>Date</code> object.
+     *
+     * @see #setTime
+     * @see #getDate
+     * @internal
+     */
+    public void setDate(Date date) {
+        setTime(date.getTime());
+    }
+
+    /**
+     * Set the current date and time of this <code>CalendarAstronomer</code> object.  All
+     * astronomical calculations are performed based on this time setting.
+     *
+     * @param jdn   the desired time, expressed as a "julian day number",
+     *              which is the number of elapsed days since
+     *              1/1/4713 BC (Julian), 12:00 GMT.  Note that julian day
+     *              numbers start at <em>noon</em>.  To get the jdn for
+     *              the corresponding midnight, subtract 0.5.
+     *
+     * @see #getJulianDay
+     * @see #JULIAN_EPOCH_MS
+     * @internal
+     */
+    public void setJulianDay(double jdn) {
+        time = (long)(jdn * DAY_MS) + JULIAN_EPOCH_MS;
+        clearCache();
+        julianDay = jdn;
+    }
+
+    /**
+     * Get the current time of this <code>CalendarAstronomer</code> object,
+     * represented as the number of milliseconds since
+     * 1/1/1970 AD 0:00 GMT (Gregorian).
+     *
+     * @see #setTime
+     * @see #getDate
+     * @internal
+     */
+    public long getTime() {
+        return time;
+    }
+
+    /**
+     * Get the current time of this <code>CalendarAstronomer</code> object,
+     * represented as a <code>Date</code> object.
+     *
+     * @see #setDate
+     * @see #getTime
+     * @internal
+     */
+    public Date getDate() {
+        return new Date(time);
+    }
+
+    /**
+     * Get the current time of this <code>CalendarAstronomer</code> object,
+     * expressed as a "julian day number", which is the number of elapsed
+     * days since 1/1/4713 BC (Julian), 12:00 GMT.
+     *
+     * @see #setJulianDay
+     * @see #JULIAN_EPOCH_MS
+     * @internal
+     */
+    public double getJulianDay() {
+        if (julianDay == INVALID) {
+            julianDay = (double)(time - JULIAN_EPOCH_MS) / (double)DAY_MS;
+        }
+        return julianDay;
+    }
+
+    /**
+     * Return this object's time expressed in julian centuries:
+     * the number of centuries after 1/1/1900 AD, 12:00 GMT
+     *
+     * @see #getJulianDay
+     * @internal
+     */
+    public double getJulianCentury() {
+        if (julianCentury == INVALID) {
+            julianCentury = (getJulianDay() - 2415020.0) / 36525;
+        }
+        return julianCentury;
+    }
+
+    /**
+     * Returns the current Greenwich sidereal time, measured in hours
+     * @internal
+     */
+    public double getGreenwichSidereal() {
+        if (siderealTime == INVALID) {
+            // See page 86 of "Practical Astronomy with your Calculator",
+            // by Peter Duffet-Smith, for details on the algorithm.
+
+            double UT = normalize((double)time/HOUR_MS, 24);
+
+            siderealTime = normalize(getSiderealOffset() + UT*1.002737909, 24);
+        }
+        return siderealTime;
+    }
+
+    private double getSiderealOffset() {
+        if (siderealT0 == INVALID) {
+            double JD  = Math.floor(getJulianDay() - 0.5) + 0.5;
+            double S   = JD - 2451545.0;
+            double T   = S / 36525.0;
+            siderealT0 = normalize(6.697374558 + 2400.051336*T + 0.000025862*T*T, 24);
+        }
+        return siderealT0;
+    }
+
+    /**
+     * Returns the current local sidereal time, measured in hours
+     * @internal
+     */
+    public double getLocalSidereal() {
+        return normalize(getGreenwichSidereal() + (double)fGmtOffset/HOUR_MS, 24);
+    }
+
+    /**
+     * Converts local sidereal time to Universal Time.
+     *
+     * @param lst   The Local Sidereal Time, in hours since sidereal midnight
+     *              on this object's current date.
+     *
+     * @return      The corresponding Universal Time, in milliseconds since
+     *              1 Jan 1970, GMT.
+     */
+    private long lstToUT(double lst) {
+        // Convert to local mean time
+        double lt = normalize((lst - getSiderealOffset()) * 0.9972695663, 24);
+
+        // Then find local midnight on this day
+        long base = DAY_MS * ((time + fGmtOffset)/DAY_MS) - fGmtOffset;
+
+        //out("    lt  =" + lt + " hours");
+        //out("    base=" + new Date(base));
+
+        return base + (long)(lt * HOUR_MS);
+    }
+
+
+    //-------------------------------------------------------------------------
+    // Coordinate transformations, all based on the current time of this object
+    //-------------------------------------------------------------------------
+
+    /**
+     * Convert from ecliptic to equatorial coordinates.
+     *
+     * @param ecliptic  A point in the sky in ecliptic coordinates.
+     * @return          The corresponding point in equatorial coordinates.
+     * @internal
+     */
+    public final Equatorial eclipticToEquatorial(Ecliptic ecliptic)
+    {
+        return eclipticToEquatorial(ecliptic.longitude, ecliptic.latitude);
+    }
+
+    /**
+     * Convert from ecliptic to equatorial coordinates.
+     *
+     * @param eclipLong     The ecliptic longitude
+     * @param eclipLat      The ecliptic latitude
+     *
+     * @return              The corresponding point in equatorial coordinates.
+     * @internal
+     */
+    public final Equatorial eclipticToEquatorial(double eclipLong, double eclipLat)
+    {
+        // See page 42 of "Practical Astronomy with your Calculator",
+        // by Peter Duffet-Smith, for details on the algorithm.
+
+        double obliq = eclipticObliquity();
+        double sinE = Math.sin(obliq);
+        double cosE = Math.cos(obliq);
+
+        double sinL = Math.sin(eclipLong);
+        double cosL = Math.cos(eclipLong);
+
+        double sinB = Math.sin(eclipLat);
+        double cosB = Math.cos(eclipLat);
+        double tanB = Math.tan(eclipLat);
+
+        return new Equatorial(Math.atan2(sinL*cosE - tanB*sinE, cosL),
+                               Math.asin(sinB*cosE + cosB*sinE*sinL) );
+    }
+
+    /**
+     * Convert from ecliptic longitude to equatorial coordinates.
+     *
+     * @param eclipLong     The ecliptic longitude
+     *
+     * @return              The corresponding point in equatorial coordinates.
+     * @internal
+     */
+    public final Equatorial eclipticToEquatorial(double eclipLong)
+    {
+        return eclipticToEquatorial(eclipLong, 0);  // TODO: optimize
+    }
+
+    /**
+     * @internal
+     */
+    public Horizon eclipticToHorizon(double eclipLong)
+    {
+        Equatorial equatorial = eclipticToEquatorial(eclipLong);
+
+        double H = getLocalSidereal()*PI/12 - equatorial.ascension;     // Hour-angle
+
+        double sinH = Math.sin(H);
+        double cosH = Math.cos(H);
+        double sinD = Math.sin(equatorial.declination);
+        double cosD = Math.cos(equatorial.declination);
+        double sinL = Math.sin(fLatitude);
+        double cosL = Math.cos(fLatitude);
+
+        double altitude = Math.asin(sinD*sinL + cosD*cosL*cosH);
+        double azimuth  = Math.atan2(-cosD*cosL*sinH, sinD - sinL * Math.sin(altitude));
+
+        return new Horizon(azimuth, altitude);
+    }
+
+
+    //-------------------------------------------------------------------------
+    // The Sun
+    //-------------------------------------------------------------------------
+
+    //
+    // Parameters of the Sun's orbit as of the epoch Jan 0.0 1990
+    // Angles are in radians (after multiplying by PI/180)
+    //
+    static final double JD_EPOCH = 2447891.5; // Julian day of epoch
+
+    static final double SUN_ETA_G   = 279.403303 * PI/180; // Ecliptic longitude at epoch
+    static final double SUN_OMEGA_G = 282.768422 * PI/180; // Ecliptic longitude of perigee
+    static final double SUN_E      =   0.016713;          // Eccentricity of orbit
+    //double sunR0     =   1.495585e8;        // Semi-major axis in KM
+    //double sunTheta0 =   0.533128 * PI/180; // Angular diameter at R0
+
+    // The following three methods, which compute the sun parameters
+    // given above for an arbitrary epoch (whatever time the object is
+    // set to), make only a small difference as compared to using the
+    // above constants.  E.g., Sunset times might differ by ~12
+    // seconds.  Furthermore, the eta-g computation is befuddled by
+    // Duffet-Smith's incorrect coefficients (p.86).  I've corrected
+    // the first-order coefficient but the others may be off too - no
+    // way of knowing without consulting another source.
+
+//  /**
+//   * Return the sun's ecliptic longitude at perigee for the current time.
+//   * See Duffett-Smith, p. 86.
+//   * @return radians
+//   */
+//  private double getSunOmegaG() {
+//      double T = getJulianCentury();
+//      return (281.2208444 + (1.719175 + 0.000452778*T)*T) * DEG_RAD;
+//  }
+
+//  /**
+//   * Return the sun's ecliptic longitude for the current time.
+//   * See Duffett-Smith, p. 86.
+//   * @return radians
+//   */
+//  private double getSunEtaG() {
+//      double T = getJulianCentury();
+//      //return (279.6966778 + (36000.76892 + 0.0003025*T)*T) * DEG_RAD;
+//      //
+//      // The above line is from Duffett-Smith, and yields manifestly wrong
+//      // results.  The below constant is derived empirically to match the
+//      // constant he gives for the 1990 EPOCH.
+//      //
+//      return (279.6966778 + (-0.3262541582718024 + 0.0003025*T)*T) * DEG_RAD;
+//  }
+
+//  /**
+//   * Return the sun's eccentricity of orbit for the current time.
+//   * See Duffett-Smith, p. 86.
+//   * @return double
+//   */
+//  private double getSunE() {
+//      double T = getJulianCentury();
+//      return 0.01675104 - (0.0000418 + 0.000000126*T)*T;
+//  }
+
+    /**
+     * The longitude of the sun at the time specified by this object.
+     * The longitude is measured in radians along the ecliptic
+     * from the "first point of Aries," the point at which the ecliptic
+     * crosses the earth's equatorial plane at the vernal equinox.
+     * <p>
+     * Currently, this method uses an approximation of the two-body Kepler's
+     * equation for the earth and the sun.  It does not take into account the
+     * perturbations caused by the other planets, the moon, etc.
+     * @internal
+     */
+    public double getSunLongitude()
+    {
+        // See page 86 of "Practical Astronomy with your Calculator",
+        // by Peter Duffet-Smith, for details on the algorithm.
+
+        if (sunLongitude == INVALID) {
+            double[] result = getSunLongitude(getJulianDay());
+            sunLongitude = result[0];
+            meanAnomalySun = result[1];
+        }
+        return sunLongitude;
+    }
+
+    /**
+     * TODO Make this public when the entire class is package-private.
+     */
+    /*public*/ double[] getSunLongitude(double julian)
+    {
+        // See page 86 of "Practical Astronomy with your Calculator",
+        // by Peter Duffet-Smith, for details on the algorithm.
+
+        double day = julian - JD_EPOCH;       // Days since epoch
+
+        // Find the angular distance the sun in a fictitious
+        // circular orbit has travelled since the epoch.
+        double epochAngle = norm2PI(PI2/TROPICAL_YEAR*day);
+
+        // The epoch wasn't at the sun's perigee; find the angular distance
+        // since perigee, which is called the "mean anomaly"
+        double meanAnomaly = norm2PI(epochAngle + SUN_ETA_G - SUN_OMEGA_G);
+
+        // Now find the "true anomaly", e.g. the real solar longitude
+        // by solving Kepler's equation for an elliptical orbit
+        // NOTE: The 3rd ed. of the book lists omega_g and eta_g in different
+        // equations; omega_g is to be correct.
+        return new double[] {
+            norm2PI(trueAnomaly(meanAnomaly, SUN_E) + SUN_OMEGA_G),
+            meanAnomaly
+        };
+    }
+
+    /**
+     * The position of the sun at this object's current date and time,
+     * in equatorial coordinates.
+     * @internal
+     */
+    public Equatorial getSunPosition() {
+        return eclipticToEquatorial(getSunLongitude(), 0);
+    }
+
+    private static class SolarLongitude {
+        double value;
+        SolarLongitude(double val) { value = val; }
+    }
+
+    /**
+     * Constant representing the vernal equinox.
+     * For use with {@link #getSunTime(SolarLongitude, boolean) getSunTime}.
+     * Note: In this case, "vernal" refers to the northern hemisphere's seasons.
+     * @internal
+     */
+    public static final SolarLongitude VERNAL_EQUINOX  = new SolarLongitude(0);
+
+    /**
+     * Constant representing the summer solstice.
+     * For use with {@link #getSunTime(SolarLongitude, boolean) getSunTime}.
+     * Note: In this case, "summer" refers to the northern hemisphere's seasons.
+     * @internal
+     */
+    public static final SolarLongitude SUMMER_SOLSTICE = new SolarLongitude(PI/2);
+
+    /**
+     * Constant representing the autumnal equinox.
+     * For use with {@link #getSunTime(SolarLongitude, boolean) getSunTime}.
+     * Note: In this case, "autumn" refers to the northern hemisphere's seasons.
+     * @internal
+     */
+    public static final SolarLongitude AUTUMN_EQUINOX  = new SolarLongitude(PI);
+
+    /**
+     * Constant representing the winter solstice.
+     * For use with {@link #getSunTime(SolarLongitude, boolean) getSunTime}.
+     * Note: In this case, "winter" refers to the northern hemisphere's seasons.
+     * @internal
+     */
+    public static final SolarLongitude WINTER_SOLSTICE = new SolarLongitude((PI*3)/2);
+
+    /**
+     * Find the next time at which the sun's ecliptic longitude will have
+     * the desired value.
+     * @internal
+     */
+    public long getSunTime(double desired, boolean next)
+    {
+        return timeOfAngle( new AngleFunc() { @Override
+        public double eval() { return getSunLongitude(); } },
+                            desired,
+                            TROPICAL_YEAR,
+                            MINUTE_MS,
+                            next);
+    }
+
+    /**
+     * Find the next time at which the sun's ecliptic longitude will have
+     * the desired value.
+     * @internal
+     */
+    public long getSunTime(SolarLongitude desired, boolean next) {
+        return getSunTime(desired.value, next);
+    }
+
+    /**
+     * Returns the time (GMT) of sunrise or sunset on the local date to which
+     * this calendar is currently set.
+     *
+     * NOTE: This method only works well if this object is set to a
+     * time near local noon.  Because of variations between the local
+     * official time zone and the geographic longitude, the
+     * computation can flop over into an adjacent day if this object
+     * is set to a time near local midnight.
+     *
+     * @internal
+     */
+    public long getSunRiseSet(boolean rise) {
+        long t0 = time;
+
+        // Make a rough guess: 6am or 6pm local time on the current day
+        long noon = ((time + fGmtOffset)/DAY_MS)*DAY_MS - fGmtOffset + 12*HOUR_MS;
+
+        setTime(noon + (rise ? -6L : 6L) * HOUR_MS);
+
+        long t = riseOrSet(new CoordFunc() {
+            @Override
+            public Equatorial eval() { return getSunPosition(); }
+            },
+                rise,
+                .533 * DEG_RAD,        // Angular Diameter
+                34 /60.0 * DEG_RAD,    // Refraction correction
+                MINUTE_MS / 12);       // Desired accuracy
+
+            setTime(t0);
+            return t;
+        }
+
+// Commented out - currently unused. ICU 2.6, Alan
+//    //-------------------------------------------------------------------------
+//    // Alternate Sun Rise/Set
+//    // See Duffett-Smith p.93
+//    //-------------------------------------------------------------------------
+//
+//    // This yields worse results (as compared to USNO data) than getSunRiseSet().
+//    /**
+//     * TODO Make this public when the entire class is package-private.
+//     */
+//    /*public*/ long getSunRiseSet2(boolean rise) {
+//        // 1. Calculate coordinates of the sun's center for midnight
+//        double jd = Math.floor(getJulianDay() - 0.5) + 0.5;
+//        double[] sl = getSunLongitude(jd);
+//        double lambda1 = sl[0];
+//        Equatorial pos1 = eclipticToEquatorial(lambda1, 0);
+//
+//        // 2. Add ... to lambda to get position 24 hours later
+//        double lambda2 = lambda1 + 0.985647*DEG_RAD;
+//        Equatorial pos2 = eclipticToEquatorial(lambda2, 0);
+//
+//        // 3. Calculate LSTs of rising and setting for these two positions
+//        double tanL = Math.tan(fLatitude);
+//        double H = Math.acos(-tanL * Math.tan(pos1.declination));
+//        double lst1r = (PI2 + pos1.ascension - H) * 24 / PI2;
+//        double lst1s = (pos1.ascension + H) * 24 / PI2;
+//               H = Math.acos(-tanL * Math.tan(pos2.declination));
+//        double lst2r = (PI2-H + pos2.ascension ) * 24 / PI2;
+//        double lst2s = (H + pos2.ascension ) * 24 / PI2;
+//        if (lst1r > 24) lst1r -= 24;
+//        if (lst1s > 24) lst1s -= 24;
+//        if (lst2r > 24) lst2r -= 24;
+//        if (lst2s > 24) lst2s -= 24;
+//
+//        // 4. Convert LSTs to GSTs.  If GST1 > GST2, add 24 to GST2.
+//        double gst1r = lstToGst(lst1r);
+//        double gst1s = lstToGst(lst1s);
+//        double gst2r = lstToGst(lst2r);
+//        double gst2s = lstToGst(lst2s);
+//        if (gst1r > gst2r) gst2r += 24;
+//        if (gst1s > gst2s) gst2s += 24;
+//
+//        // 5. Calculate GST at 0h UT of this date
+//        double t00 = utToGst(0);
+//
+//        // 6. Calculate GST at 0h on the observer's longitude
+//        double offset = Math.round(fLongitude*12/PI); // p.95 step 6; he _rounds_ to nearest 15 deg.
+//        double t00p = t00 - offset*1.002737909;
+//        if (t00p < 0) t00p += 24; // do NOT normalize
+//
+//        // 7. Adjust
+//        if (gst1r < t00p) {
+//            gst1r += 24;
+//            gst2r += 24;
+//        }
+//        if (gst1s < t00p) {
+//            gst1s += 24;
+//            gst2s += 24;
+//        }
+//
+//        // 8.
+//        double gstr = (24.07*gst1r-t00*(gst2r-gst1r))/(24.07+gst1r-gst2r);
+//        double gsts = (24.07*gst1s-t00*(gst2s-gst1s))/(24.07+gst1s-gst2s);
+//
+//        // 9. Correct for parallax, refraction, and sun's diameter
+//        double dec = (pos1.declination + pos2.declination) / 2;
+//        double psi = Math.acos(Math.sin(fLatitude) / Math.cos(dec));
+//        double x = 0.830725 * DEG_RAD; // parallax+refraction+diameter
+//        double y = Math.asin(Math.sin(x) / Math.sin(psi)) * RAD_DEG;
+//        double delta_t = 240 * y / Math.cos(dec) / 3600; // hours
+//
+//        // 10. Add correction to GSTs, subtract from GSTr
+//        gstr -= delta_t;
+//        gsts += delta_t;
+//
+//        // 11. Convert GST to UT and then to local civil time
+//        double ut = gstToUt(rise ? gstr : gsts);
+//        //System.out.println((rise?"rise=":"set=") + ut + ", delta_t=" + delta_t);
+//        long midnight = DAY_MS * (time / DAY_MS); // Find UT midnight on this day
+//        return midnight + (long) (ut * 3600000);
+//    }
+
+// Commented out - currently unused. ICU 2.6, Alan
+//    /**
+//     * Convert local sidereal time to Greenwich sidereal time.
+//     * Section 15.  Duffett-Smith p.21
+//     * @param lst in hours (0..24)
+//     * @return GST in hours (0..24)
+//     */
+//    double lstToGst(double lst) {
+//        double delta = fLongitude * 24 / PI2;
+//        return normalize(lst - delta, 24);
+//    }
+
+// Commented out - currently unused. ICU 2.6, Alan
+//    /**
+//     * Convert UT to GST on this date.
+//     * Section 12.  Duffett-Smith p.17
+//     * @param ut in hours
+//     * @return GST in hours
+//     */
+//    double utToGst(double ut) {
+//        return normalize(getT0() + ut*1.002737909, 24);
+//    }
+
+// Commented out - currently unused. ICU 2.6, Alan
+//    /**
+//     * Convert GST to UT on this date.
+//     * Section 13.  Duffett-Smith p.18
+//     * @param gst in hours
+//     * @return UT in hours
+//     */
+//    double gstToUt(double gst) {
+//        return normalize(gst - getT0(), 24) * 0.9972695663;
+//    }
+
+// Commented out - currently unused. ICU 2.6, Alan
+//    double getT0() {
+//        // Common computation for UT <=> GST
+//
+//        // Find JD for 0h UT
+//        double jd = Math.floor(getJulianDay() - 0.5) + 0.5;
+//
+//        double s = jd - 2451545.0;
+//        double t = s / 36525.0;
+//        double t0 = 6.697374558 + (2400.051336 + 0.000025862*t)*t;
+//        return t0;
+//    }
+
+// Commented out - currently unused. ICU 2.6, Alan
+//    //-------------------------------------------------------------------------
+//    // Alternate Sun Rise/Set
+//    // See sci.astro FAQ
+//    // http://www.faqs.org/faqs/astronomy/faq/part3/section-5.html
+//    //-------------------------------------------------------------------------
+//
+//    // Note: This method appears to produce inferior accuracy as
+//    // compared to getSunRiseSet().
+//
+//    /**
+//     * TODO Make this public when the entire class is package-private.
+//     */
+//    /*public*/ long getSunRiseSet3(boolean rise) {
+//
+//        // Compute day number for 0.0 Jan 2000 epoch
+//        double d = (double)(time - EPOCH_2000_MS) / DAY_MS;
+//
+//        // Now compute the Local Sidereal Time, LST:
+//        //
+//        double LST  =  98.9818  +  0.985647352 * d  +  /*UT*15  +  long*/
+//            fLongitude*RAD_DEG;
+//        //
+//        // (east long. positive).  Note that LST is here expressed in degrees,
+//        // where 15 degrees corresponds to one hour.  Since LST really is an angle,
+//        // it's convenient to use one unit---degrees---throughout.
+//
+//        //     COMPUTING THE SUN'S POSITION
+//        //     ----------------------------
+//        //
+//        // To be able to compute the Sun's rise/set times, you need to be able to
+//        // compute the Sun's position at any time.  First compute the "day
+//        // number" d as outlined above, for the desired moment.  Next compute:
+//        //
+//        double oblecl = 23.4393 - 3.563E-7 * d;
+//        //
+//        double w  =  282.9404  +  4.70935E-5   * d;
+//        double M  =  356.0470  +  0.9856002585 * d;
+//        double e  =  0.016709  -  1.151E-9     * d;
+//        //
+//        // This is the obliquity of the ecliptic, plus some of the elements of
+//        // the Sun's apparent orbit (i.e., really the Earth's orbit): w =
+//        // argument of perihelion, M = mean anomaly, e = eccentricity.
+//        // Semi-major axis is here assumed to be exactly 1.0 (while not strictly
+//        // true, this is still an accurate approximation).  Next compute E, the
+//        // eccentric anomaly:
+//        //
+//        double E = M + e*(180/PI) * Math.sin(M*DEG_RAD) * ( 1.0 + e*Math.cos(M*DEG_RAD) );
+//        //
+//        // where E and M are in degrees.  This is it---no further iterations are
+//        // needed because we know e has a sufficiently small value.  Next compute
+//        // the true anomaly, v, and the distance, r:
+//        //
+//        /*      r * cos(v)  =  */ double A  =  Math.cos(E*DEG_RAD) - e;
+//        /*      r * sin(v)  =  */ double B  =  Math.sqrt(1 - e*e) * Math.sin(E*DEG_RAD);
+//        //
+//        // and
+//        //
+//        //      r  =  sqrt( A*A + B*B )
+//        double v  =  Math.atan2( B, A )*RAD_DEG;
+//        //
+//        // The Sun's true longitude, slon, can now be computed:
+//        //
+//        double slon  =  v + w;
+//        //
+//        // Since the Sun is always at the ecliptic (or at least very very close to
+//        // it), we can use simplified formulae to convert slon (the Sun's ecliptic
+//        // longitude) to sRA and sDec (the Sun's RA and Dec):
+//        //
+//        //                   sin(slon) * cos(oblecl)
+//        //     tan(sRA)  =  -------------------------
+//        //             cos(slon)
+//        //
+//        //     sin(sDec) =  sin(oblecl) * sin(slon)
+//        //
+//        // As was the case when computing az, the Azimuth, if possible use an
+//        // atan2() function to compute sRA.
+//
+//        double sRA = Math.atan2(Math.sin(slon*DEG_RAD) * Math.cos(oblecl*DEG_RAD), Math.cos(slon*DEG_RAD))*RAD_DEG;
+//
+//        double sin_sDec = Math.sin(oblecl*DEG_RAD) * Math.sin(slon*DEG_RAD);
+//        double sDec = Math.asin(sin_sDec)*RAD_DEG;
+//
+//        //     COMPUTING RISE AND SET TIMES
+//        //     ----------------------------
+//        //
+//        // To compute when an object rises or sets, you must compute when it
+//        // passes the meridian and the HA of rise/set.  Then the rise time is
+//        // the meridian time minus HA for rise/set, and the set time is the
+//        // meridian time plus the HA for rise/set.
+//        //
+//        // To find the meridian time, compute the Local Sidereal Time at 0h local
+//        // time (or 0h UT if you prefer to work in UT) as outlined above---name
+//        // that quantity LST0.  The Meridian Time, MT, will now be:
+//        //
+//        //     MT  =  RA - LST0
+//        double MT = normalize(sRA - LST, 360);
+//        //
+//        // where "RA" is the object's Right Ascension (in degrees!).  If negative,
+//        // add 360 deg to MT.  If the object is the Sun, leave the time as it is,
+//        // but if it's stellar, multiply MT by 365.2422/366.2422, to convert from
+//        // sidereal to solar time.  Now, compute HA for rise/set, name that
+//        // quantity HA0:
+//        //
+//        //                 sin(h0)  -  sin(lat) * sin(Dec)
+//        // cos(HA0)  =  ---------------------------------
+//        //                      cos(lat) * cos(Dec)
+//        //
+//        // where h0 is the altitude selected to represent rise/set.  For a purely
+//        // mathematical horizon, set h0 = 0 and simplify to:
+//        //
+//        //     cos(HA0)  =  - tan(lat) * tan(Dec)
+//        //
+//        // If you want to account for refraction on the atmosphere, set h0 = -35/60
+//        // degrees (-35 arc minutes), and if you want to compute the rise/set times
+//        // for the Sun's upper limb, set h0 = -50/60 (-50 arc minutes).
+//        //
+//        double h0 = -50/60 * DEG_RAD;
+//
+//        double HA0 = Math.acos(
+//          (Math.sin(h0) - Math.sin(fLatitude) * sin_sDec) /
+//          (Math.cos(fLatitude) * Math.cos(sDec*DEG_RAD)))*RAD_DEG;
+//
+//        // When HA0 has been computed, leave it as it is for the Sun but multiply
+//        // by 365.2422/366.2422 for stellar objects, to convert from sidereal to
+//        // solar time.  Finally compute:
+//        //
+//        //    Rise time  =  MT - HA0
+//        //    Set  time  =  MT + HA0
+//        //
+//        // convert the times from degrees to hours by dividing by 15.
+//        //
+//        // If you'd like to check that your calculations are accurate or just
+//        // need a quick result, check the USNO's Sun or Moon Rise/Set Table,
+//        // <URL:http://aa.usno.navy.mil/AA/data/docs/RS_OneYear.html>.
+//
+//        double result = MT + (rise ? -HA0 : HA0); // in degrees
+//
+//        // Find UT midnight on this day
+//        long midnight = DAY_MS * (time / DAY_MS);
+//
+//        return midnight + (long) (result * 3600000 / 15);
+//    }
+
+    //-------------------------------------------------------------------------
+    // The Moon
+    //-------------------------------------------------------------------------
+
+    static final double moonL0 = 318.351648 * PI/180;   // Mean long. at epoch
+    static final double moonP0 =  36.340410 * PI/180;   // Mean long. of perigee
+    static final double moonN0 = 318.510107 * PI/180;   // Mean long. of node
+    static final double moonI  =   5.145366 * PI/180;   // Inclination of orbit
+    static final double moonE  =   0.054900;            // Eccentricity of orbit
+
+    // These aren't used right now
+    static final double moonA  =   3.84401e5;           // semi-major axis (km)
+    static final double moonT0 =   0.5181 * PI/180;     // Angular size at distance A
+    static final double moonPi =   0.9507 * PI/180;     // Parallax at distance A
+
+    /**
+     * The position of the moon at the time set on this
+     * object, in equatorial coordinates.
+     * @internal
+     */
+    public Equatorial getMoonPosition()
+    {
+        //
+        // See page 142 of "Practical Astronomy with your Calculator",
+        // by Peter Duffet-Smith, for details on the algorithm.
+        //
+        if (moonPosition == null) {
+            // Calculate the solar longitude.  Has the side effect of
+            // filling in "meanAnomalySun" as well.
+            double sunLong = getSunLongitude();
+
+            //
+            // Find the # of days since the epoch of our orbital parameters.
+            // TODO: Convert the time of day portion into ephemeris time
+            //
+            double day = getJulianDay() - JD_EPOCH;       // Days since epoch
+
+            // Calculate the mean longitude and anomaly of the moon, based on
+            // a circular orbit.  Similar to the corresponding solar calculation.
+            double meanLongitude = norm2PI(13.1763966*PI/180*day + moonL0);
+            double meanAnomalyMoon = norm2PI(meanLongitude - 0.1114041*PI/180 * day - moonP0);
+
+            //
+            // Calculate the following corrections:
+            //  Evection:   the sun's gravity affects the moon's eccentricity
+            //  Annual Eqn: variation in the effect due to earth-sun distance
+            //  A3:         correction factor (for ???)
+            //
+            double evection = 1.2739*PI/180 * Math.sin(2 * (meanLongitude - sunLong)
+                                                - meanAnomalyMoon);
+            double annual   = 0.1858*PI/180 * Math.sin(meanAnomalySun);
+            double a3       = 0.3700*PI/180 * Math.sin(meanAnomalySun);
+
+            meanAnomalyMoon += evection - annual - a3;
+
+            //
+            // More correction factors:
+            //  center  equation of the center correction
+            //  a4      yet another error correction (???)
+            //
+            // TODO: Skip the equation of the center correction and solve Kepler's eqn?
+            //
+            double center = 6.2886*PI/180 * Math.sin(meanAnomalyMoon);
+            double a4 =     0.2140*PI/180 * Math.sin(2 * meanAnomalyMoon);
+
+            // Now find the moon's corrected longitude
+            moonLongitude = meanLongitude + evection + center - annual + a4;
+
+            //
+            // And finally, find the variation, caused by the fact that the sun's
+            // gravitational pull on the moon varies depending on which side of
+            // the earth the moon is on
+            //
+            double variation = 0.6583*PI/180 * Math.sin(2*(moonLongitude - sunLong));
+
+            moonLongitude += variation;
+
+            //
+            // What we've calculated so far is the moon's longitude in the plane
+            // of its own orbit.  Now map to the ecliptic to get the latitude
+            // and longitude.  First we need to find the longitude of the ascending
+            // node, the position on the ecliptic where it is crossed by the moon's
+            // orbit as it crosses from the southern to the northern hemisphere.
+            //
+            double nodeLongitude = norm2PI(moonN0 - 0.0529539*PI/180 * day);
+
+            nodeLongitude -= 0.16*PI/180 * Math.sin(meanAnomalySun);
+
+            double y = Math.sin(moonLongitude - nodeLongitude);
+            double x = Math.cos(moonLongitude - nodeLongitude);
+
+            moonEclipLong = Math.atan2(y*Math.cos(moonI), x) + nodeLongitude;
+            double moonEclipLat = Math.asin(y * Math.sin(moonI));
+
+            moonPosition = eclipticToEquatorial(moonEclipLong, moonEclipLat);
+        }
+        return moonPosition;
+    }
+
+    /**
+     * The "age" of the moon at the time specified in this object.
+     * This is really the angle between the
+     * current ecliptic longitudes of the sun and the moon,
+     * measured in radians.
+     *
+     * @see #getMoonPhase
+     * @internal
+     */
+    public double getMoonAge() {
+        // See page 147 of "Practical Astronomy with your Calculator",
+        // by Peter Duffet-Smith, for details on the algorithm.
+        //
+        // Force the moon's position to be calculated.  We're going to use
+        // some the intermediate results cached during that calculation.
+        //
+        getMoonPosition();
+
+        return norm2PI(moonEclipLong - sunLongitude);
+    }
+
+    /**
+     * Calculate the phase of the moon at the time set in this object.
+     * The returned phase is a <code>double</code> in the range
+     * <code>0 <= phase < 1</code>, interpreted as follows:
+     * <ul>
+     * <li>0.00: New moon
+     * <li>0.25: First quarter
+     * <li>0.50: Full moon
+     * <li>0.75: Last quarter
+     * </ul>
+     *
+     * @see #getMoonAge
+     * @internal
+     */
+    public double getMoonPhase() {
+        // See page 147 of "Practical Astronomy with your Calculator",
+        // by Peter Duffet-Smith, for details on the algorithm.
+        return 0.5 * (1 - Math.cos(getMoonAge()));
+    }
+
+    private static class MoonAge {
+        double value;
+        MoonAge(double val) { value = val; }
+    }
+
+    /**
+     * Constant representing a new moon.
+     * For use with {@link #getMoonTime(MoonAge, boolean) getMoonTime}
+     * @internal
+     */
+    public static final MoonAge NEW_MOON      = new MoonAge(0);
+
+    /**
+     * Constant representing the moon's first quarter.
+     * For use with {@link #getMoonTime(MoonAge, boolean) getMoonTime}
+     * @internal
+     */
+    public static final MoonAge FIRST_QUARTER = new MoonAge(PI/2);
+
+    /**
+     * Constant representing a full moon.
+     * For use with {@link #getMoonTime(MoonAge, boolean) getMoonTime}
+     * @internal
+     */
+    public static final MoonAge FULL_MOON     = new MoonAge(PI);
+
+    /**
+     * Constant representing the moon's last quarter.
+     * For use with {@link #getMoonTime(MoonAge, boolean) getMoonTime}
+     * @internal
+     */
+    public static final MoonAge LAST_QUARTER  = new MoonAge((PI*3)/2);
+
+    /**
+     * Find the next or previous time at which the Moon's ecliptic
+     * longitude will have the desired value.
+     * <p>
+     * @param desired   The desired longitude.
+     * @param next      <tt>true</tt> if the next occurrance of the phase
+     *                  is desired, <tt>false</tt> for the previous occurrance.
+     * @internal
+     */
+    public long getMoonTime(double desired, boolean next)
+    {
+        return timeOfAngle( new AngleFunc() {
+                            @Override
+                            public double eval() { return getMoonAge(); } },
+                            desired,
+                            SYNODIC_MONTH,
+                            MINUTE_MS,
+                            next);
+    }
+
+    /**
+     * Find the next or previous time at which the moon will be in the
+     * desired phase.
+     * <p>
+     * @param desired   The desired phase of the moon.
+     * @param next      <tt>true</tt> if the next occurrance of the phase
+     *                  is desired, <tt>false</tt> for the previous occurrance.
+     * @internal
+     */
+    public long getMoonTime(MoonAge desired, boolean next) {
+        return getMoonTime(desired.value, next);
+    }
+
+    /**
+     * Returns the time (GMT) of sunrise or sunset on the local date to which
+     * this calendar is currently set.
+     * @internal
+     */
+    public long getMoonRiseSet(boolean rise)
+    {
+        return riseOrSet(new CoordFunc() {
+                            @Override
+                            public Equatorial eval() { return getMoonPosition(); }
+                         },
+                         rise,
+                         .533 * DEG_RAD,        // Angular Diameter
+                         34 /60.0 * DEG_RAD,    // Refraction correction
+                         MINUTE_MS);            // Desired accuracy
+    }
+
+    //-------------------------------------------------------------------------
+    // Interpolation methods for finding the time at which a given event occurs
+    //-------------------------------------------------------------------------
+
+    private interface AngleFunc {
+        public double eval();
+    }
+
+    private long timeOfAngle(AngleFunc func, double desired,
+                             double periodDays, long epsilon, boolean next)
+    {
+        // Find the value of the function at the current time
+        double lastAngle = func.eval();
+
+        // Find out how far we are from the desired angle
+        double deltaAngle = norm2PI(desired - lastAngle) ;
+
+        // Using the average period, estimate the next (or previous) time at
+        // which the desired angle occurs.
+        double deltaT =  (deltaAngle + (next ? 0 : -PI2)) * (periodDays*DAY_MS) / PI2;
+
+        double lastDeltaT = deltaT; // Liu
+        long startTime = time; // Liu
+
+        setTime(time + (long)deltaT);
+
+        // Now iterate until we get the error below epsilon.  Throughout
+        // this loop we use normPI to get values in the range -Pi to Pi,
+        // since we're using them as correction factors rather than absolute angles.
+        do {
+            // Evaluate the function at the time we've estimated
+            double angle = func.eval();
+
+            // Find the # of milliseconds per radian at this point on the curve
+            double factor = Math.abs(deltaT / normPI(angle-lastAngle));
+
+            // Correct the time estimate based on how far off the angle is
+            deltaT = normPI(desired - angle) * factor;
+
+            // HACK:
+            //
+            // If abs(deltaT) begins to diverge we need to quit this loop.
+            // This only appears to happen when attempting to locate, for
+            // example, a new moon on the day of the new moon.  E.g.:
+            //
+            // This result is correct:
+            // newMoon(7508(Mon Jul 23 00:00:00 CST 1990,false))=
+            //   Sun Jul 22 10:57:41 CST 1990
+            //
+            // But attempting to make the same call a day earlier causes deltaT
+            // to diverge:
+            // CalendarAstronomer.timeOfAngle() diverging: 1.348508727575625E9 ->
+            //   1.3649828540224032E9
+            // newMoon(7507(Sun Jul 22 00:00:00 CST 1990,false))=
+            //   Sun Jul 08 13:56:15 CST 1990
+            //
+            // As a temporary solution, we catch this specific condition and
+            // adjust our start time by one eighth period days (either forward
+            // or backward) and try again.
+            // Liu 11/9/00
+            if (Math.abs(deltaT) > Math.abs(lastDeltaT)) {
+                long delta = (long) (periodDays * DAY_MS / 8);
+                setTime(startTime + (next ? delta : -delta));
+                return timeOfAngle(func, desired, periodDays, epsilon, next);
+            }
+
+            lastDeltaT = deltaT;
+            lastAngle = angle;
+
+            setTime(time + (long)deltaT);
+        }
+        while (Math.abs(deltaT) > epsilon);
+
+        return time;
+    }
+
+    private interface CoordFunc {
+        public Equatorial eval();
+    }
+
+    private long riseOrSet(CoordFunc func, boolean rise,
+                           double diameter, double refraction,
+                           long epsilon)
+    {
+        Equatorial  pos = null;
+        double      tanL   = Math.tan(fLatitude);
+        long        deltaT = Long.MAX_VALUE;
+        int         count = 0;
+
+        //
+        // Calculate the object's position at the current time, then use that
+        // position to calculate the time of rising or setting.  The position
+        // will be different at that time, so iterate until the error is allowable.
+        //
+        do {
+            // See "Practical Astronomy With Your Calculator, section 33.
+            pos = func.eval();
+            double angle = Math.acos(-tanL * Math.tan(pos.declination));
+            double lst = ((rise ? PI2-angle : angle) + pos.ascension ) * 24 / PI2;
+
+            // Convert from LST to Universal Time.
+            long newTime = lstToUT( lst );
+
+            deltaT = newTime - time;
+            setTime(newTime);
+        }
+        while (++ count < 5 && Math.abs(deltaT) > epsilon);
+
+        // Calculate the correction due to refraction and the object's angular diameter
+        double cosD  = Math.cos(pos.declination);
+        double psi   = Math.acos(Math.sin(fLatitude) / cosD);
+        double x     = diameter / 2 + refraction;
+        double y     = Math.asin(Math.sin(x) / Math.sin(psi));
+        long  delta  = (long)((240 * y * RAD_DEG / cosD)*SECOND_MS);
+
+        return time + (rise ? -delta : delta);
+    }
+
+    //-------------------------------------------------------------------------
+    // Other utility methods
+    //-------------------------------------------------------------------------
+
+    /***
+     * Given 'value', add or subtract 'range' until 0 <= 'value' < range.
+     * The modulus operator.
+     */
+    private static final double normalize(double value, double range) {
+        return value - range * Math.floor(value / range);
+    }
+
+    /**
+     * Normalize an angle so that it's in the range 0 - 2pi.
+     * For positive angles this is just (angle % 2pi), but the Java
+     * mod operator doesn't work that way for negative numbers....
+     */
+    private static final double norm2PI(double angle) {
+        return normalize(angle, PI2);
+    }
+
+    /**
+     * Normalize an angle into the range -PI - PI
+     */
+    private static final double normPI(double angle) {
+        return normalize(angle + PI, PI2) - PI;
+    }
+
+    /**
+     * Find the "true anomaly" (longitude) of an object from
+     * its mean anomaly and the eccentricity of its orbit.  This uses
+     * an iterative solution to Kepler's equation.
+     *
+     * @param meanAnomaly   The object's longitude calculated as if it were in
+     *                      a regular, circular orbit, measured in radians
+     *                      from the point of perigee.
+     *
+     * @param eccentricity  The eccentricity of the orbit
+     *
+     * @return The true anomaly (longitude) measured in radians
+     */
+    private double trueAnomaly(double meanAnomaly, double eccentricity)
+    {
+        // First, solve Kepler's equation iteratively
+        // Duffett-Smith, p.90
+        double delta;
+        double E = meanAnomaly;
+        do {
+            delta = E - eccentricity * Math.sin(E) - meanAnomaly;
+            E = E - delta / (1 - eccentricity * Math.cos(E));
+        }
+        while (Math.abs(delta) > 1e-5); // epsilon = 1e-5 rad
+
+        return 2.0 * Math.atan( Math.tan(E/2) * Math.sqrt( (1+eccentricity)
+                                                          /(1-eccentricity) ) );
+    }
+
+    /**
+     * Return the obliquity of the ecliptic (the angle between the ecliptic
+     * and the earth's equator) at the current time.  This varies due to
+     * the precession of the earth's axis.
+     *
+     * @return  the obliquity of the ecliptic relative to the equator,
+     *          measured in radians.
+     */
+    private double eclipticObliquity() {
+        if (eclipObliquity == INVALID) {
+            final double epoch = 2451545.0;     // 2000 AD, January 1.5
+
+            double T = (getJulianDay() - epoch) / 36525;
+
+            eclipObliquity = 23.439292
+                           - 46.815/3600 * T
+                           - 0.0006/3600 * T*T
+                           + 0.00181/3600 * T*T*T;
+
+            eclipObliquity *= DEG_RAD;
+        }
+        return eclipObliquity;
+    }
+
+
+    //-------------------------------------------------------------------------
+    // Private data
+    //-------------------------------------------------------------------------
+
+    /**
+     * Current time in milliseconds since 1/1/1970 AD
+     * @see java.util.Date#getTime
+     */
+    private long time;
+
+    /* These aren't used yet, but they'll be needed for sunset calculations
+     * and equatorial to horizon coordinate conversions
+     */
+    private double fLongitude = 0.0;
+    private double fLatitude  = 0.0;
+    private long   fGmtOffset = 0;
+
+    //
+    // The following fields are used to cache calculated results for improved
+    // performance.  These values all depend on the current time setting
+    // of this object, so the clearCache method is provided.
+    //
+    static final private double INVALID = Double.MIN_VALUE;
+
+    private transient double    julianDay       = INVALID;
+    private transient double    julianCentury   = INVALID;
+    private transient double    sunLongitude    = INVALID;
+    private transient double    meanAnomalySun  = INVALID;
+    private transient double    moonLongitude   = INVALID;
+    private transient double    moonEclipLong   = INVALID;
+    //private transient double    meanAnomalyMoon = INVALID;
+    private transient double    eclipObliquity  = INVALID;
+    private transient double    siderealT0      = INVALID;
+    private transient double    siderealTime    = INVALID;
+
+    private transient Equatorial  moonPosition = null;
+
+    private void clearCache() {
+        julianDay       = INVALID;
+        julianCentury   = INVALID;
+        sunLongitude    = INVALID;
+        meanAnomalySun  = INVALID;
+        moonLongitude   = INVALID;
+        moonEclipLong   = INVALID;
+        //meanAnomalyMoon = INVALID;
+        eclipObliquity  = INVALID;
+        siderealTime    = INVALID;
+        siderealT0      = INVALID;
+        moonPosition    = null;
+    }
+
+    //private static void out(String s) {
+    //    System.out.println(s);
+    //}
+
+    //private static String deg(double rad) {
+    //    return Double.toString(rad * RAD_DEG);
+    //}
+
+    //private static String hours(long ms) {
+    //    return Double.toString((double)ms / HOUR_MS) + " hours";
+    //}
+
+    /**
+     * @internal
+     */
+    public String local(long localMillis) {
+        return new Date(localMillis - TimeZone.getDefault().getRawOffset()).toString();
+    }
+
+
+    /**
+     * Represents the position of an object in the sky relative to the ecliptic,
+     * the plane of the earth's orbit around the Sun.
+     * This is a spherical coordinate system in which the latitude
+     * specifies the position north or south of the plane of the ecliptic.
+     * The longitude specifies the position along the ecliptic plane
+     * relative to the "First Point of Aries", which is the Sun's position in the sky
+     * at the Vernal Equinox.
+     * <p>
+     * Note that Ecliptic objects are immutable and cannot be modified
+     * once they are constructed.  This allows them to be passed and returned by
+     * value without worrying about whether other code will modify them.
+     *
+     * @see CalendarAstronomer.Equatorial
+     * @see CalendarAstronomer.Horizon
+     * @internal
+     */
+    public static final class Ecliptic {
+        /**
+         * Constructs an Ecliptic coordinate object.
+         * <p>
+         * @param lat The ecliptic latitude, measured in radians.
+         * @param lon The ecliptic longitude, measured in radians.
+         * @internal
+         */
+        public Ecliptic(double lat, double lon) {
+            latitude = lat;
+            longitude = lon;
+        }
+
+        /**
+         * Return a string representation of this object
+         * @internal
+         */
+        @Override
+        public String toString() {
+            return Double.toString(longitude*RAD_DEG) + "," + (latitude*RAD_DEG);
+        }
+
+        /**
+         * The ecliptic latitude, in radians.  This specifies an object's
+         * position north or south of the plane of the ecliptic,
+         * with positive angles representing north.
+         * @internal
+         */
+        public final double latitude;
+
+        /**
+         * The ecliptic longitude, in radians.
+         * This specifies an object's position along the ecliptic plane
+         * relative to the "First Point of Aries", which is the Sun's position
+         * in the sky at the Vernal Equinox,
+         * with positive angles representing east.
+         * <p>
+         * A bit of trivia: the first point of Aries is currently in the
+         * constellation Pisces, due to the precession of the earth's axis.
+         * @internal
+         */
+        public final double longitude;
+    }
+
+    /**
+     * Represents the position of an
+     * object in the sky relative to the plane of the earth's equator.
+     * The <i>Right Ascension</i> specifies the position east or west
+     * along the equator, relative to the sun's position at the vernal
+     * equinox.  The <i>Declination</i> is the position north or south
+     * of the equatorial plane.
+     * <p>
+     * Note that Equatorial objects are immutable and cannot be modified
+     * once they are constructed.  This allows them to be passed and returned by
+     * value without worrying about whether other code will modify them.
+     *
+     * @see CalendarAstronomer.Ecliptic
+     * @see CalendarAstronomer.Horizon
+     * @internal
+     */
+    public static final class Equatorial {
+        /**
+         * Constructs an Equatorial coordinate object.
+         * <p>
+         * @param asc The right ascension, measured in radians.
+         * @param dec The declination, measured in radians.
+         * @internal
+         */
+        public Equatorial(double asc, double dec) {
+            ascension = asc;
+            declination = dec;
+        }
+
+        /**
+         * Return a string representation of this object, with the
+         * angles measured in degrees.
+         * @internal
+         */
+        @Override
+        public String toString() {
+            return Double.toString(ascension*RAD_DEG) + "," + (declination*RAD_DEG);
+        }
+
+        /**
+         * Return a string representation of this object with the right ascension
+         * measured in hours, minutes, and seconds.
+         * @internal
+         */
+        public String toHmsString() {
+            return radToHms(ascension) + "," + radToDms(declination);
+        }
+
+        /**
+         * The right ascension, in radians.
+         * This is the position east or west along the equator
+         * relative to the sun's position at the vernal equinox,
+         * with positive angles representing East.
+         * @internal
+         */
+        public final double ascension;
+
+        /**
+         * The declination, in radians.
+         * This is the position north or south of the equatorial plane,
+         * with positive angles representing north.
+         * @internal
+         */
+        public final double declination;
+    }
+
+    /**
+     * Represents the position of an  object in the sky relative to
+     * the local horizon.
+     * The <i>Altitude</i> represents the object's elevation above the horizon,
+     * with objects below the horizon having a negative altitude.
+     * The <i>Azimuth</i> is the geographic direction of the object from the
+     * observer's position, with 0 representing north.  The azimuth increases
+     * clockwise from north.
+     * <p>
+     * Note that Horizon objects are immutable and cannot be modified
+     * once they are constructed.  This allows them to be passed and returned by
+     * value without worrying about whether other code will modify them.
+     *
+     * @see CalendarAstronomer.Ecliptic
+     * @see CalendarAstronomer.Equatorial
+     * @internal
+     */
+    public static final class Horizon {
+        /**
+         * Constructs a Horizon coordinate object.
+         * <p>
+         * @param alt  The altitude, measured in radians above the horizon.
+         * @param azim The azimuth, measured in radians clockwise from north.
+         * @internal
+         */
+        public Horizon(double alt, double azim) {
+            altitude = alt;
+            azimuth = azim;
+        }
+
+        /**
+         * Return a string representation of this object, with the
+         * angles measured in degrees.
+         * @internal
+         */
+        @Override
+        public String toString() {
+            return Double.toString(altitude*RAD_DEG) + "," + (azimuth*RAD_DEG);
+        }
+
+        /**
+         * The object's altitude above the horizon, in radians.
+         * @internal
+         */
+        public final double altitude;
+
+        /**
+         * The object's direction, in radians clockwise from north.
+         * @internal
+         */
+        public final double azimuth;
+    }
+
+    static private String radToHms(double angle) {
+        int hrs = (int) (angle*RAD_HOUR);
+        int min = (int)((angle*RAD_HOUR - hrs) * 60);
+        int sec = (int)((angle*RAD_HOUR - hrs - min/60.0) * 3600);
+
+        return Integer.toString(hrs) + "h" + min + "m" + sec + "s";
+    }
+
+    static private String radToDms(double angle) {
+        int deg = (int) (angle*RAD_DEG);
+        int min = (int)((angle*RAD_DEG - deg) * 60);
+        int sec = (int)((angle*RAD_DEG - deg - min/60.0) * 3600);
+
+        return Integer.toString(deg) + "\u00b0" + min + "'" + sec + "\"";
+    }
+}
diff --git a/icu4j/Android.bp b/icu4j/Android.bp
index 45867d6b3..beaca6a33 100644
--- a/icu4j/Android.bp
+++ b/icu4j/Android.bp
@@ -103,21 +103,6 @@ java_library {
     ],
 }
 
-// Small static library used by TwilightService in the system server and WallpaperPicker2 app. To
-// avoid @CorePlaformApi, the system server doesn't use CalendarAstronomer in android.icu.
-// Don't link this in boot classpath or Zygote to avoid class collision with the
-// com.ibm.icu.impl.CalendarAstronomer in the app classloader.
-java_library_static {
-    name: "icu4j_calendar_astronomer",
-    host_supported: false,
-    sdk_version: "core_current",
-    srcs: ["main/core/src/main/java/com/ibm/icu/impl/CalendarAstronomer.java"],
-    visibility: [
-        "//frameworks/base/services/core",
-        "//packages/apps/WallpaperPicker2",
-    ],
-}
-
 java_test {
     name: "icu4j-tests",
     defaults: ["icu4j-defaults"],