1454 lines
52 KiB
C++
1454 lines
52 KiB
C++
/************************************************************************
|
|
* Copyright (C) 1996-2003, International Business Machines Corporation *
|
|
* and others. All Rights Reserved. *
|
|
************************************************************************
|
|
* 2003-nov-07 srl Port from Java
|
|
*/
|
|
|
|
#include "astro.h"
|
|
|
|
#if !UCONFIG_NO_FORMATTING
|
|
|
|
#include "unicode/calendar.h"
|
|
#include "math.h"
|
|
#include <float.h>
|
|
#include "unicode/putil.h"
|
|
#include <stdio.h> // for toString()
|
|
|
|
#ifdef U_DEBUG_ASTRO
|
|
# include "uresimp.h" // for debugging
|
|
|
|
static void debug_astro_loc(const char *f, int32_t l)
|
|
{
|
|
fprintf(stderr, "%s:%d: ", f, l);
|
|
}
|
|
|
|
static void debug_astro_msg(const char *pat, ...)
|
|
{
|
|
va_list ap;
|
|
va_start(ap, pat);
|
|
vfprintf(stderr, pat, ap);
|
|
fflush(stderr);
|
|
}
|
|
#include "unicode/datefmt.h"
|
|
#include "unicode/ustring.h"
|
|
static const char * debug_astro_date(UDate d) {
|
|
static char gStrBuf[1024];
|
|
static DateFormat *df = NULL;
|
|
if(df == NULL) {
|
|
df = DateFormat::createDateTimeInstance(DateFormat::MEDIUM, DateFormat::MEDIUM, Locale::getUS());
|
|
df->adoptTimeZone(TimeZone::getGMT()->clone());
|
|
}
|
|
UnicodeString str;
|
|
df->format(d,str);
|
|
u_austrncpy(gStrBuf,str.getTerminatedBuffer(),sizeof(gStrBuf)-1);
|
|
return gStrBuf;
|
|
}
|
|
|
|
// must use double parens, i.e.: U_DEBUG_ASTRO_MSG(("four is: %d",4));
|
|
#define U_DEBUG_ASTRO_MSG(x) {debug_astro_loc(__FILE__,__LINE__);debug_astro_msg x;}
|
|
#else
|
|
#define U_DEBUG_ASTRO_MSG(x)
|
|
#endif
|
|
|
|
static inline UBool isINVALID(double d) {
|
|
return(uprv_isNaN(d));
|
|
}
|
|
|
|
/**
|
|
* The number of standard hours in one sidereal day.
|
|
* Approximately 24.93.
|
|
* @internal
|
|
* @deprecated ICU 2.4. This class may be removed or modified.
|
|
*/
|
|
const double CalendarAstronomer::SIDEREAL_DAY = 23.93446960027;
|
|
|
|
/**
|
|
* The number of sidereal hours in one mean solar day.
|
|
* Approximately 24.07.
|
|
* @internal
|
|
* @deprecated ICU 2.4. This class may be removed or modified.
|
|
*/
|
|
const double CalendarAstronomer::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
|
|
* @deprecated ICU 2.4. This class may be removed or modified.
|
|
*/
|
|
const double CalendarAstronomer::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
|
|
* @deprecated ICU 2.4. This class may be removed or modified.
|
|
*/
|
|
const double CalendarAstronomer::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
|
|
* @deprecated ICU 2.4. This class may be removed or modified.
|
|
*/
|
|
const double CalendarAstronomer::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
|
|
* @deprecated ICU 2.4. This class may be removed or modified.
|
|
*/
|
|
const double CalendarAstronomer::SIDEREAL_YEAR = 365.25636;
|
|
|
|
//-------------------------------------------------------------------------
|
|
// Time-related constants
|
|
//-------------------------------------------------------------------------
|
|
|
|
/**
|
|
* The number of milliseconds in one second.
|
|
* @internal
|
|
* @deprecated ICU 2.4. This class may be removed or modified.
|
|
*/
|
|
const int32_t CalendarAstronomer::SECOND_MS = 1000;
|
|
|
|
/**
|
|
* The number of milliseconds in one minute.
|
|
* @internal
|
|
* @deprecated ICU 2.4. This class may be removed or modified.
|
|
*/
|
|
const int32_t CalendarAstronomer::MINUTE_MS = 60*SECOND_MS;
|
|
|
|
/**
|
|
* The number of milliseconds in one hour.
|
|
* @internal
|
|
* @deprecated ICU 2.4. This class may be removed or modified.
|
|
*/
|
|
const int32_t CalendarAstronomer::HOUR_MS = 60*MINUTE_MS;
|
|
|
|
/**
|
|
* The number of milliseconds in one day.
|
|
* @internal
|
|
* @deprecated ICU 2.4. This class may be removed or modified.
|
|
*/
|
|
const double CalendarAstronomer::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
|
|
* @deprecated ICU 2.4. This class may be removed or modified.
|
|
*/
|
|
const double CalendarAstronomer::JULIAN_EPOCH_MS = -210866760000000.0;
|
|
|
|
|
|
/**
|
|
* Milliseconds value for 0.0 January 2000 AD.
|
|
*/
|
|
const double CalendarAstronomer::EPOCH_2000_MS = 946598400000.0;
|
|
|
|
//-------------------------------------------------------------------------
|
|
// Assorted private data used for conversions
|
|
//-------------------------------------------------------------------------
|
|
|
|
// My own copies of these so compilers are more likely to optimize them away
|
|
const double CalendarAstronomer::PI = 3.14159265358979323846;
|
|
const double CalendarAstronomer::PI2 = CalendarAstronomer::PI * 2.0;
|
|
const double CalendarAstronomer::RAD_HOUR = 12 / CalendarAstronomer::PI; // radians -> hours
|
|
const double CalendarAstronomer::DEG_RAD = CalendarAstronomer::PI / 180; // degrees -> radians
|
|
const double CalendarAstronomer::RAD_DEG = 180 / CalendarAstronomer::PI; // radians -> degrees
|
|
|
|
//-------------------------------------------------------------------------
|
|
// Constructors
|
|
//-------------------------------------------------------------------------
|
|
|
|
/**
|
|
* Construct a new <code>CalendarAstronomer</code> object that is initialized to
|
|
* the current date and time.
|
|
* @internal
|
|
* @deprecated ICU 2.4. This class may be removed or modified.
|
|
*/
|
|
CalendarAstronomer::CalendarAstronomer():
|
|
fTime(Calendar::getNow()), moonPosition(0,0), moonPositionSet(FALSE) {
|
|
}
|
|
|
|
/**
|
|
* Construct a new <code>CalendarAstronomer</code> object that is initialized to
|
|
* the specified date and time.
|
|
* @internal
|
|
* @deprecated ICU 2.4. This class may be removed or modified.
|
|
*/
|
|
CalendarAstronomer::CalendarAstronomer(UDate d): fTime(d),moonPosition(0,0), moonPositionSet(FALSE) {
|
|
}
|
|
|
|
/**
|
|
* 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
|
|
* @deprecated ICU 2.4. This class may be removed or modified.
|
|
*/
|
|
CalendarAstronomer::CalendarAstronomer(double longitude, double latitude) :
|
|
fTime(Calendar::getNow()), moonPosition(0,0), moonPositionSet(FALSE) {
|
|
fLongitude = normPI(longitude * DEG_RAD);
|
|
fLatitude = normPI(latitude * DEG_RAD);
|
|
fGmtOffset = (double)(fLongitude * 24 * HOUR_MS / CalendarAstronomer::PI2);
|
|
}
|
|
|
|
CalendarAstronomer::~CalendarAstronomer()
|
|
{
|
|
}
|
|
|
|
//-------------------------------------------------------------------------
|
|
// 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
|
|
* @deprecated ICU 2.4. This class may be removed or modified.
|
|
*/
|
|
void CalendarAstronomer::setTime(UDate aTime) {
|
|
fTime = aTime;
|
|
U_DEBUG_ASTRO_MSG(("setTime(%.1lf, %sL)\n", aTime, debug_astro_date(aTime+fGmtOffset)));
|
|
clearCache();
|
|
}
|
|
|
|
/**
|
|
* 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
|
|
* @deprecated ICU 2.4. This class may be removed or modified.
|
|
*/
|
|
void CalendarAstronomer::setJulianDay(double jdn) {
|
|
fTime = (double)(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
|
|
* @deprecated ICU 2.4. This class may be removed or modified.
|
|
*/
|
|
UDate CalendarAstronomer::getTime() {
|
|
return fTime;
|
|
}
|
|
|
|
/**
|
|
* 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
|
|
* @deprecated ICU 2.4. This class may be removed or modified.
|
|
*/
|
|
double CalendarAstronomer::getJulianDay() {
|
|
if (isINVALID(julianDay)) {
|
|
julianDay = (fTime - (double)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
|
|
* @deprecated ICU 2.4. This class may be removed or modified.
|
|
*/
|
|
double CalendarAstronomer::getJulianCentury() {
|
|
if (isINVALID(julianCentury)) {
|
|
julianCentury = (getJulianDay() - 2415020.0) / 36525;
|
|
}
|
|
return julianCentury;
|
|
}
|
|
|
|
/**
|
|
* Returns the current Greenwich sidereal time, measured in hours
|
|
* @internal
|
|
* @deprecated ICU 2.4. This class may be removed or modified.
|
|
*/
|
|
double CalendarAstronomer::getGreenwichSidereal() {
|
|
if (isINVALID(siderealTime)) {
|
|
// See page 86 of "Practial Astronomy with your Calculator",
|
|
// by Peter Duffet-Smith, for details on the algorithm.
|
|
|
|
double UT = normalize((double)fTime/HOUR_MS, 24);
|
|
|
|
siderealTime = normalize(getSiderealOffset() + UT*1.002737909, 24);
|
|
}
|
|
return siderealTime;
|
|
}
|
|
|
|
double CalendarAstronomer::getSiderealOffset() {
|
|
if (isINVALID(siderealT0)) {
|
|
double JD = uprv_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
|
|
* @deprecated ICU 2.4. This class may be removed or modified.
|
|
*/
|
|
double CalendarAstronomer::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.
|
|
*/
|
|
double CalendarAstronomer::lstToUT(double lst) {
|
|
// Convert to local mean time
|
|
double lt = normalize((lst - getSiderealOffset()) * 0.9972695663, 24);
|
|
|
|
// Then find local midnight on this day
|
|
double base = (DAY_MS * Math::floorDivide(fTime + 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
|
|
* @deprecated ICU 2.4. This class may be removed or modified.
|
|
*/
|
|
CalendarAstronomer::Equatorial& CalendarAstronomer::eclipticToEquatorial(CalendarAstronomer::Equatorial& result, const CalendarAstronomer::Ecliptic& ecliptic)
|
|
{
|
|
return eclipticToEquatorial(result, 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
|
|
* @deprecated ICU 2.4. This class may be removed or modified.
|
|
*/
|
|
CalendarAstronomer::Equatorial& CalendarAstronomer::eclipticToEquatorial(CalendarAstronomer::Equatorial& result, double eclipLong, double eclipLat)
|
|
{
|
|
// See page 42 of "Practial Astronomy with your Calculator",
|
|
// by Peter Duffet-Smith, for details on the algorithm.
|
|
|
|
double obliq = eclipticObliquity();
|
|
double sinE = ::sin(obliq);
|
|
double cosE = cos(obliq);
|
|
|
|
double sinL = ::sin(eclipLong);
|
|
double cosL = cos(eclipLong);
|
|
|
|
double sinB = ::sin(eclipLat);
|
|
double cosB = cos(eclipLat);
|
|
double tanB = tan(eclipLat);
|
|
|
|
result.set(atan2(sinL*cosE - tanB*sinE, cosL),
|
|
asin(sinB*cosE + cosB*sinE*sinL) );
|
|
return result;
|
|
}
|
|
|
|
/**
|
|
* Convert from ecliptic longitude to equatorial coordinates.
|
|
*
|
|
* @param eclipLong The ecliptic longitude
|
|
*
|
|
* @return The corresponding point in equatorial coordinates.
|
|
* @internal
|
|
* @deprecated ICU 2.4. This class may be removed or modified.
|
|
*/
|
|
CalendarAstronomer::Equatorial& CalendarAstronomer::eclipticToEquatorial(CalendarAstronomer::Equatorial& result, double eclipLong)
|
|
{
|
|
return eclipticToEquatorial(result, eclipLong, 0); // TODO: optimize
|
|
}
|
|
|
|
/**
|
|
* @internal
|
|
* @deprecated ICU 2.4. This class may be removed or modified.
|
|
*/
|
|
CalendarAstronomer::Horizon& CalendarAstronomer::eclipticToHorizon(CalendarAstronomer::Horizon& result, double eclipLong)
|
|
{
|
|
Equatorial equatorial;
|
|
eclipticToEquatorial(equatorial, eclipLong);
|
|
|
|
double H = getLocalSidereal()*CalendarAstronomer::PI/12 - equatorial.ascension; // Hour-angle
|
|
|
|
double sinH = ::sin(H);
|
|
double cosH = cos(H);
|
|
double sinD = ::sin(equatorial.declination);
|
|
double cosD = cos(equatorial.declination);
|
|
double sinL = ::sin(fLatitude);
|
|
double cosL = cos(fLatitude);
|
|
|
|
double altitude = asin(sinD*sinL + cosD*cosL*cosH);
|
|
double azimuth = atan2(-cosD*cosL*sinH, sinD - sinL * ::sin(altitude));
|
|
|
|
result.set(azimuth, altitude);
|
|
return result;
|
|
}
|
|
|
|
|
|
//-------------------------------------------------------------------------
|
|
// The Sun
|
|
//-------------------------------------------------------------------------
|
|
|
|
//
|
|
// Parameters of the Sun's orbit as of the epoch Jan 0.0 1990
|
|
// Angles are in radians (after multiplying by CalendarAstronomer::PI/180)
|
|
//
|
|
const double CalendarAstronomer::JD_EPOCH = 2447891.5; // Julian day of epoch
|
|
|
|
const double CalendarAstronomer::SUN_ETA_G = 279.403303 * CalendarAstronomer::PI/180; // Ecliptic longitude at epoch
|
|
const double CalendarAstronomer::SUN_OMEGA_G = 282.768422 * CalendarAstronomer::PI/180; // Ecliptic longitude of perigee
|
|
const double CalendarAstronomer::SUN_E = 0.016713; // Eccentricity of orbit
|
|
//double sunR0 = 1.495585e8; // Semi-major axis in KM
|
|
//double sunTheta0 = 0.533128 * CalendarAstronomer::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
|
|
* @deprecated ICU 2.4. This class may be removed or modified.
|
|
*/
|
|
double CalendarAstronomer::getSunLongitude()
|
|
{
|
|
// See page 86 of "Practial Astronomy with your Calculator",
|
|
// by Peter Duffet-Smith, for details on the algorithm.
|
|
|
|
if (isINVALID(sunLongitude)) {
|
|
getSunLongitude(getJulianDay(), sunLongitude, meanAnomalySun);
|
|
}
|
|
return sunLongitude;
|
|
}
|
|
|
|
/**
|
|
* TODO Make this public when the entire class is package-private.
|
|
*/
|
|
/*public*/ void CalendarAstronomer::getSunLongitude(double julianDay, double &longitude, double &meanAnomaly)
|
|
{
|
|
// See page 86 of "Practial Astronomy with your Calculator",
|
|
// by Peter Duffet-Smith, for details on the algorithm.
|
|
|
|
double day = julianDay - 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"
|
|
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.
|
|
longitude = norm2PI(trueAnomaly(meanAnomaly, SUN_E) + SUN_OMEGA_G);
|
|
}
|
|
|
|
/**
|
|
* The position of the sun at this object's current date and time,
|
|
* in equatorial coordinates.
|
|
* @internal
|
|
* @deprecated ICU 2.4. This class may be removed or modified.
|
|
*/
|
|
CalendarAstronomer::Equatorial& CalendarAstronomer::getSunPosition(CalendarAstronomer::Equatorial& result) {
|
|
return eclipticToEquatorial(result, getSunLongitude(), 0);
|
|
}
|
|
|
|
|
|
/**
|
|
* Constant representing the vernal equinox.
|
|
* For use with {@link #getSunTime getSunTime}.
|
|
* Note: In this case, "vernal" refers to the northern hemisphere's seasons.
|
|
* @internal
|
|
* @deprecated ICU 2.4. This class may be removed or modified.
|
|
*/
|
|
const CalendarAstronomer::SolarLongitude CalendarAstronomer::VERNAL_EQUINOX = CalendarAstronomer::SolarLongitude(0);
|
|
|
|
/**
|
|
* Constant representing the summer solstice.
|
|
* For use with {@link #getSunTime getSunTime}.
|
|
* Note: In this case, "summer" refers to the northern hemisphere's seasons.
|
|
* @internal
|
|
* @deprecated ICU 2.4. This class may be removed or modified.
|
|
*/
|
|
const CalendarAstronomer::SolarLongitude CalendarAstronomer::SUMMER_SOLSTICE = CalendarAstronomer::SolarLongitude(PI/2);
|
|
|
|
/**
|
|
* Constant representing the autumnal equinox.
|
|
* For use with {@link #getSunTime getSunTime}.
|
|
* Note: In this case, "autumn" refers to the northern hemisphere's seasons.
|
|
* @internal
|
|
* @deprecated ICU 2.4. This class may be removed or modified.
|
|
*/
|
|
const CalendarAstronomer::SolarLongitude CalendarAstronomer::AUTUMN_EQUINOX = CalendarAstronomer::SolarLongitude(PI);
|
|
|
|
/**
|
|
* Constant representing the winter solstice.
|
|
* For use with {@link #getSunTime getSunTime}.
|
|
* Note: In this case, "winter" refers to the northern hemisphere's seasons.
|
|
* @internal
|
|
* @deprecated ICU 2.4. This class may be removed or modified.
|
|
*/
|
|
const CalendarAstronomer::SolarLongitude CalendarAstronomer::WINTER_SOLSTICE = CalendarAstronomer::SolarLongitude((PI*3)/2);
|
|
|
|
/**
|
|
* Find the next time at which the sun's ecliptic longitude will have
|
|
* the desired value.
|
|
* @internal
|
|
* @deprecated ICU 2.4. This class may be removed or modified.
|
|
*/
|
|
class SunTimeAngleFunc : public CalendarAstronomer::AngleFunc {
|
|
public:
|
|
virtual double eval(CalendarAstronomer& a) { return a.getSunLongitude(); }
|
|
};
|
|
|
|
UDate CalendarAstronomer::getSunTime(double desired, UBool next)
|
|
{
|
|
SunTimeAngleFunc func;
|
|
return timeOfAngle( func,
|
|
desired,
|
|
TROPICAL_YEAR,
|
|
MINUTE_MS,
|
|
next);
|
|
}
|
|
|
|
/**
|
|
* Find the next time at which the sun's ecliptic longitude will have
|
|
* the desired value.
|
|
* @internal
|
|
* @deprecated ICU 2.4. This class may be removed or modified.
|
|
*/
|
|
UDate CalendarAstronomer::getSunTime(const SolarLongitude& desired, UBool next) {
|
|
return getSunTime(desired.value, next);
|
|
}
|
|
|
|
class RiseSetCoordFunc : public CalendarAstronomer::CoordFunc {
|
|
public:
|
|
virtual void eval(CalendarAstronomer::Equatorial& result, CalendarAstronomer&a) { a.getSunPosition(result); }
|
|
};
|
|
|
|
UDate CalendarAstronomer::getSunRiseSet(UBool rise)
|
|
{
|
|
UDate t0 = fTime;
|
|
|
|
// Make a rough guess: 6am or 6pm local time on the current day
|
|
double noon = Math::floorDivide(fTime + fGmtOffset, DAY_MS)*DAY_MS - fGmtOffset + (12*HOUR_MS);
|
|
|
|
U_DEBUG_ASTRO_MSG(("Noon=%.2lf, %sL, gmtoff %.2lf\n", noon, debug_astro_date(noon+fGmtOffset), fGmtOffset));
|
|
setTime(noon + ((rise ? -6 : 6) * HOUR_MS));
|
|
U_DEBUG_ASTRO_MSG(("added %.2lf ms as a guess,\n", ((rise ? -6. : 6.) * HOUR_MS)));
|
|
|
|
RiseSetCoordFunc func;
|
|
double t = riseOrSet(func,
|
|
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 when the entire class is package-private.
|
|
// */
|
|
// /*public*/ long getSunRiseSet2(boolean rise) {
|
|
// // 1. Calculate coordinates of the sun's center for midnight
|
|
// double jd = uprv_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 = ::tan(fLatitude);
|
|
// double H = ::acos(-tanL * ::tan(pos1.declination));
|
|
// double lst1r = (PI2 + pos1.ascension - H) * 24 / CalendarAstronomer::PI2;
|
|
// double lst1s = (pos1.ascension + H) * 24 / CalendarAstronomer::PI2;
|
|
// H = ::acos(-tanL * ::tan(pos2.declination));
|
|
// double lst2r = (PI2-H + pos2.ascension ) * 24 / CalendarAstronomer::PI2;
|
|
// double lst2s = (H + pos2.ascension ) * 24 / CalendarAstronomer::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 = ::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 = ::acos(sin(fLatitude) / cos(dec));
|
|
// double x = 0.830725 * DEG_RAD; // parallax+refraction+diameter
|
|
// double y = ::asin(sin(x) / ::sin(psi)) * RAD_DEG;
|
|
// double delta_t = 240 * y / 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 / CalendarAstronomer::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 = uprv_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 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) * ::sin(M*DEG_RAD) * ( 1.0 + e*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 = cos(E*DEG_RAD) - e;
|
|
// /* r * ::sin(v) = */ double B = ::sqrt(1 - e*e) * ::sin(E*DEG_RAD);
|
|
// //
|
|
// // and
|
|
// //
|
|
// // r = sqrt( A*A + B*B )
|
|
// double v = ::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 = ::atan2(sin(slon*DEG_RAD) * cos(oblecl*DEG_RAD), cos(slon*DEG_RAD))*RAD_DEG;
|
|
//
|
|
// double sin_sDec = ::sin(oblecl*DEG_RAD) * ::sin(slon*DEG_RAD);
|
|
// double sDec = ::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 = ::acos(
|
|
// (sin(h0) - ::sin(fLatitude) * sin_sDec) /
|
|
// (cos(fLatitude) * 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
|
|
//-------------------------------------------------------------------------
|
|
|
|
const double CalendarAstronomer::moonL0 = 318.351648 * CalendarAstronomer::PI/180; // Mean long. at epoch
|
|
const double CalendarAstronomer::moonP0 = 36.340410 * CalendarAstronomer::PI/180; // Mean long. of perigee
|
|
const double CalendarAstronomer::moonN0 = 318.510107 * CalendarAstronomer::PI/180; // Mean long. of node
|
|
const double CalendarAstronomer::moonI = 5.145366 * CalendarAstronomer::PI/180; // Inclination of orbit
|
|
const double CalendarAstronomer::moonE = 0.054900; // Eccentricity of orbit
|
|
|
|
// These aren't used right now
|
|
const double CalendarAstronomer::moonA = 3.84401e5; // semi-major axis (km)
|
|
const double CalendarAstronomer::moonT0 = 0.5181 * CalendarAstronomer::PI/180; // Angular size at distance A
|
|
const double CalendarAstronomer::moonPi = 0.9507 * CalendarAstronomer::PI/180; // Parallax at distance A
|
|
|
|
/**
|
|
* The position of the moon at the time set on this
|
|
* object, in equatorial coordinates.
|
|
* @internal
|
|
* @deprecated ICU 2.4. This class may be removed or modified.
|
|
*/
|
|
const CalendarAstronomer::Equatorial& CalendarAstronomer::getMoonPosition()
|
|
{
|
|
//
|
|
// See page 142 of "Practial Astronomy with your Calculator",
|
|
// by Peter Duffet-Smith, for details on the algorithm.
|
|
//
|
|
if (moonPositionSet == FALSE) {
|
|
// Calculate the solar longitude. Has the side effect of
|
|
// filling in "meanAnomalySun" as well.
|
|
double sunLongitude = 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 * ::sin(2 * (meanLongitude - sunLongitude)
|
|
- meanAnomalyMoon);
|
|
double annual = 0.1858*PI/180 * ::sin(meanAnomalySun);
|
|
double a3 = 0.3700*PI/180 * ::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 * ::sin(meanAnomalyMoon);
|
|
double a4 = 0.2140*PI/180 * ::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*CalendarAstronomer::PI/180 * ::sin(2*(moonLongitude - sunLongitude));
|
|
|
|
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 * ::sin(meanAnomalySun);
|
|
|
|
double y = ::sin(moonLongitude - nodeLongitude);
|
|
double x = cos(moonLongitude - nodeLongitude);
|
|
|
|
moonEclipLong = ::atan2(y*cos(moonI), x) + nodeLongitude;
|
|
double moonEclipLat = ::asin(y * ::sin(moonI));
|
|
|
|
eclipticToEquatorial(moonPosition, moonEclipLong, moonEclipLat);
|
|
moonPositionSet = TRUE;
|
|
}
|
|
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
|
|
* @deprecated ICU 2.4. This class may be removed or modified.
|
|
*/
|
|
double CalendarAstronomer::getMoonAge() {
|
|
// See page 147 of "Practial 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
|
|
* @deprecated ICU 2.4. This class may be removed or modified.
|
|
*/
|
|
double CalendarAstronomer::getMoonPhase() {
|
|
// See page 147 of "Practial Astronomy with your Calculator",
|
|
// by Peter Duffet-Smith, for details on the algorithm.
|
|
return 0.5 * (1 - cos(getMoonAge()));
|
|
}
|
|
|
|
/**
|
|
* Constant representing a new moon.
|
|
* For use with {@link #getMoonTime getMoonTime}
|
|
* @internal
|
|
* @deprecated ICU 2.4. This class may be removed or modified.
|
|
*/
|
|
const CalendarAstronomer::MoonAge CalendarAstronomer::NEW_MOON = CalendarAstronomer::MoonAge(0);
|
|
|
|
/**
|
|
* Constant representing the moon's first quarter.
|
|
* For use with {@link #getMoonTime getMoonTime}
|
|
* @internal
|
|
* @deprecated ICU 2.4. This class may be removed or modified.
|
|
*/
|
|
const CalendarAstronomer::MoonAge CalendarAstronomer::FIRST_QUARTER = CalendarAstronomer::MoonAge(CalendarAstronomer::PI/2);
|
|
|
|
/**
|
|
* Constant representing a full moon.
|
|
* For use with {@link #getMoonTime getMoonTime}
|
|
* @internal
|
|
* @deprecated ICU 2.4. This class may be removed or modified.
|
|
*/
|
|
const CalendarAstronomer::MoonAge CalendarAstronomer::FULL_MOON = CalendarAstronomer::MoonAge(CalendarAstronomer::PI);
|
|
|
|
/**
|
|
* Constant representing the moon's last quarter.
|
|
* For use with {@link #getMoonTime getMoonTime}
|
|
* @internal
|
|
* @deprecated ICU 2.4. This class may be removed or modified.
|
|
*/
|
|
|
|
class MoonTimeAngleFunc : public CalendarAstronomer::AngleFunc {
|
|
public:
|
|
virtual double eval(CalendarAstronomer&a) { return a.getMoonAge(); }
|
|
};
|
|
|
|
const CalendarAstronomer::MoonAge CalendarAstronomer::LAST_QUARTER = CalendarAstronomer::MoonAge((CalendarAstronomer::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
|
|
* @deprecated ICU 2.4. This class may be removed or modified.
|
|
*/
|
|
UDate CalendarAstronomer::getMoonTime(double desired, UBool next)
|
|
{
|
|
MoonTimeAngleFunc func;
|
|
return timeOfAngle( func,
|
|
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
|
|
* @deprecated ICU 2.4. This class may be removed or modified.
|
|
*/
|
|
UDate CalendarAstronomer::getMoonTime(const CalendarAstronomer::MoonAge& desired, UBool next) {
|
|
return getMoonTime(desired.value, next);
|
|
}
|
|
|
|
class MoonRiseSetCoordFunc : public CalendarAstronomer::CoordFunc {
|
|
public:
|
|
virtual void eval(CalendarAstronomer::Equatorial& result, CalendarAstronomer&a) { result = a.getMoonPosition(); }
|
|
};
|
|
|
|
/**
|
|
* Returns the time (GMT) of sunrise or sunset on the local date to which
|
|
* this calendar is currently set.
|
|
* @internal
|
|
* @deprecated ICU 2.4. This class may be removed or modified.
|
|
*/
|
|
UDate CalendarAstronomer::getMoonRiseSet(UBool rise)
|
|
{
|
|
MoonRiseSetCoordFunc func;
|
|
return riseOrSet(func,
|
|
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
|
|
//-------------------------------------------------------------------------
|
|
|
|
UDate CalendarAstronomer::timeOfAngle(AngleFunc& func, double desired,
|
|
double periodDays, double epsilon, UBool next)
|
|
{
|
|
// Find the value of the function at the current time
|
|
double lastAngle = func.eval(*this);
|
|
|
|
// 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 ? 0.0 : -CalendarAstronomer::PI2)) * (periodDays*CalendarAstronomer::DAY_MS) / CalendarAstronomer::PI2;
|
|
|
|
double lastDeltaT = deltaT; // Liu
|
|
UDate startTime = fTime; // Liu
|
|
|
|
setTime(fTime + (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(*this);
|
|
|
|
// Find the # of milliseconds per radian at this point on the curve
|
|
double factor = uprv_fabs(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 (uprv_fabs(deltaT) > uprv_fabs(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(fTime + (long)deltaT);
|
|
}
|
|
while (uprv_fabs(deltaT) > epsilon);
|
|
|
|
return fTime;
|
|
}
|
|
|
|
UDate CalendarAstronomer::riseOrSet(CoordFunc& func, UBool rise,
|
|
double diameter, double refraction,
|
|
double epsilon)
|
|
{
|
|
Equatorial pos;
|
|
double tanL = ::tan(fLatitude);
|
|
double deltaT = 0;
|
|
int32_t 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.
|
|
//
|
|
U_DEBUG_ASTRO_MSG(("setup rise=%s, dia=%.3lf, ref=%.3lf, eps=%.3lf\n",
|
|
rise?"T":"F", diameter, refraction, epsilon));
|
|
do {
|
|
// See "Practical Astronomy With Your Calculator, section 33.
|
|
func.eval(pos, *this);
|
|
double angle = ::acos(-tanL * ::tan(pos.declination));
|
|
double lst = ((rise ? CalendarAstronomer::PI2-angle : angle) + pos.ascension ) * 24 / CalendarAstronomer::PI2;
|
|
|
|
// Convert from LST to Universal Time.
|
|
UDate newTime = lstToUT( lst );
|
|
|
|
deltaT = newTime - fTime;
|
|
setTime(newTime);
|
|
U_DEBUG_ASTRO_MSG(("%d] dT=%.3lf, angle=%.3lf, lst=%.3lf, A=%.3lf/D=%.3lf\n",
|
|
count, deltaT, angle, lst, pos->ascension, pos->declination));
|
|
}
|
|
while (++ count < 5 && uprv_fabs(deltaT) > epsilon);
|
|
|
|
// Calculate the correction due to refraction and the object's angular diameter
|
|
double cosD = ::cos(pos.declination);
|
|
double psi = ::acos(sin(fLatitude) / cosD);
|
|
double x = diameter / 2 + refraction;
|
|
double y = ::asin(sin(x) / ::sin(psi));
|
|
long delta = (long)((240 * y * RAD_DEG / cosD)*SECOND_MS);
|
|
|
|
return fTime + (rise ? -delta : delta);
|
|
}
|
|
|
|
/**
|
|
* 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
|
|
*/
|
|
double CalendarAstronomer::trueAnomaly(double meanAnomaly, double eccentricity)
|
|
{
|
|
// First, solve Kepler's equation iteratively
|
|
// Duffett-Smith, p.90
|
|
double delta;
|
|
double E = meanAnomaly;
|
|
do {
|
|
delta = E - eccentricity * ::sin(E) - meanAnomaly;
|
|
E = E - delta / (1 - eccentricity * ::cos(E));
|
|
}
|
|
while (uprv_fabs(delta) > 1e-5); // epsilon = 1e-5 rad
|
|
|
|
return 2.0 * ::atan( ::tan(E/2) * ::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.
|
|
*/
|
|
double CalendarAstronomer::eclipticObliquity() {
|
|
if (isINVALID(eclipObliquity)) {
|
|
const 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
|
|
//-------------------------------------------------------------------------
|
|
void CalendarAstronomer::clearCache() {
|
|
const double INVALID = uprv_getNaN();
|
|
|
|
julianDay = INVALID;
|
|
julianCentury = INVALID;
|
|
sunLongitude = INVALID;
|
|
meanAnomalySun = INVALID;
|
|
moonLongitude = INVALID;
|
|
moonEclipLong = INVALID;
|
|
meanAnomalyMoon = INVALID;
|
|
eclipObliquity = INVALID;
|
|
siderealTime = INVALID;
|
|
siderealT0 = INVALID;
|
|
moonPositionSet = FALSE;
|
|
}
|
|
|
|
//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
|
|
* @deprecated ICU 2.4. This class may be removed or modified.
|
|
*/
|
|
UDate CalendarAstronomer::local(UDate localMillis) {
|
|
// TODO - srl ?
|
|
TimeZone *tz = TimeZone::createDefault();
|
|
int32_t rawOffset;
|
|
int32_t dstOffset;
|
|
UErrorCode status = U_ZERO_ERROR;
|
|
tz->getOffset(localMillis, TRUE, rawOffset, dstOffset, status);
|
|
delete tz;
|
|
return localMillis - rawOffset;
|
|
}
|
|
|
|
// Debugging functions
|
|
UnicodeString CalendarAstronomer::Ecliptic::toString() const
|
|
{
|
|
char tmp[800];
|
|
sprintf(tmp, "[%.5f,%.5f]", longitude*RAD_DEG, latitude*RAD_DEG);
|
|
return UnicodeString(tmp, "");
|
|
}
|
|
|
|
UnicodeString CalendarAstronomer::Equatorial::toString() const
|
|
{
|
|
char tmp[400];
|
|
sprintf(tmp, "%f,%f",
|
|
(ascension*RAD_DEG), (declination*RAD_DEG));
|
|
return UnicodeString(tmp, "");
|
|
}
|
|
|
|
UnicodeString CalendarAstronomer::Horizon::toString() const
|
|
{
|
|
char tmp[800];
|
|
sprintf(tmp, "[%.5f,%.5f]", altitude*RAD_DEG, azimuth*RAD_DEG);
|
|
return UnicodeString(tmp, "");
|
|
}
|
|
|
|
|
|
// 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 + "\"";
|
|
// }
|
|
|
|
|
|
|
|
#endif // !UCONFIG_NO_FORMATTING
|