Package gaiasky.util.coord

Class AstroUtils

  • public class AstroUtils
extends java.lang.Object
    Some astronomical goodies to get the position of the Sun, Moon, work out Julian dates, etc.

    • Field Summary

      Fields 
      Modifier and Type Field Description
      static long J2000_MS
      Milliseconds of J2000 in the scale of java.util.Date
      static double JD_J2000
      Julian date of J2000 epoch (julian days since January 1, 4713 BCE)
      static double JD_J2010
      Julian date of TGAS epoch 2010-01-01T00:00:00
      static double JD_J2015
      Julian date of reference epoch J2015.0 = JD2455197.5 = 2015-01-01T00:00:00
      static double JD_J2015_5
      Julian date of the Gaia DR2 reference epoch, J2015.5 = JD2455197.5 = 2015-01-01T00:00:00

    • Constructor Summary

      Constructors 
      Constructor Description
      AstroUtils()  

    • Method Summary

      All Methods Static Methods Concrete Methods Deprecated Methods 
      Modifier and Type Method Description
      static int[] getCalendarDay​(double julianDate)
      Gets the Gregorian calendar quantities given the Julian date.
      static double getDayFraction​(int hour, int min, int sec, int nanos)
      Gets the day fraction from the day quantities
      static int[] getDayQuantities​(double dayFraction)
      Gets the day quantities from the day fraction
      static double getDaysSinceJ2000​(java.time.Instant date)
      Returns the elapsed days since the epoch J2000 until the given date.
      static Vector3d getEclipticCoordinates​(java.lang.String body, java.time.Instant instant, Vector3d out, boolean highAccuracy)
      Returns a vector with the heliocentric ecliptic latitude and longitude in radians and the distance in internal units.
      static double getJulianDate​(double refEpoch)
      Get julian date from a double reference epoch
      static double getJulianDate​(int year, int month, int day, int hour, int min, int sec, int nanos, boolean gregorian)
      Gets the Julian date number given the Gregorian calendar quantities.
      static double getJulianDate​(java.time.Instant instant)  
      static double getJulianDateCache​(java.time.Instant instant)
      Gets the Julian Date for the given date.
      static double getJulianDayNumberBook​(int year, int month, int day)
      Deprecated.
      This does not work well!
      static double getJulianDayNumberWikipediaGregorianCalendar​(int year, int month, int day)
      Returns the Julian day number of a date in the Gregorian calendar.
      static double getJulianDayNumberWikipediaJulianCalendar​(int year, int month, int day)
      Returns the Julian day number of a date in the Julian calendar.
      static double getMsSince​(java.time.Instant date, double epoch_jd)
      Returns the elapsed milliseconds since the given julian date jd until the given date.
      static double getMsSinceJ2000​(java.time.Instant date)
      Returns the elapsed milliseconds since the epoch J2000 until the given date.
      static double getMsSinceJ2010​(java.time.Instant date)
      Returns the elapsed milliseconds since the epoch J2010 until the given date.
      static double getMsSinceJ2015​(java.time.Instant date)
      Returns the elapsed milliseconds since the epoch J2015 until the given date.
      static double getSunDistance​(double jd)  
      static double getSunDistance​(java.time.Instant date)
      Algorithm in "Astronomical Algorithms" book by Jean Meeus.
      static double getSunLongitude​(java.time.Instant date)
      Returns the Sun's ecliptic longitude in degrees for the given time.
      static double getSunLongitudeWikipedia​(double jd)
      Gets the ecliptic longitude of the Sun in degrees as published in Wikipedia.
      static java.time.Instant julianDateToInstant​(double jd)  
      static Vector3d moonEclipticCoordinates​(double julianDate, Vector3d out)
      Algorithm in "Astronomical Algorithms" book by Jean Meeus.
      static Vector3d moonEclipticCoordinates​(java.time.Instant date, Vector3d out)
      Algorithm in "Astronomical Algorithms" book by Jean Meeus.
      static void moonEquatorialCoordinates​(Vector3d placeholder, double julianDate)
      Algorithm in "Astronomical Algorithms" book by Jean Meeus.
      static void moonEquatorialCoordinates​(Vector3d placeholder, java.time.Instant date)
      Algorithm in "Astronomical Algorithms" book by Jean Meeus.
      static double obliquity​(double julianDate)
      Returns the obliquity of the ecliptic (inclination of the Earth's axis of rotation) for a given date, in degrees
      static Vector3d plutoEclipticCoordinates​(double d, Vector3d out)
      Ecliptic coordinates of pluto at the given date.
      static Vector3d plutoEclipticCoordinates​(java.time.Instant date, Vector3d out)
      Ecliptic coordinates of pluto at the given date
      static Vector3d properMotionsToCartesian​(double mualphastar, double mudelta, double radvel, double ra, double dec, double distpc)
      Converts proper motions + radial velocity into a cartesian vector.
      static double T​(double julianDate)
      Time T measured in Julian centuries from the Epoch J2000.0
      static double tau​(double julianDate)  

      • Methods inherited from class java.lang.Object

        clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

    • Field Detail

      • JD_J2000

        public static final double JD_J2000
        Julian date of J2000 epoch (julian days since January 1, 4713 BCE)

      • JD_J2015

        public static final double JD_J2015
        Julian date of reference epoch J2015.0 = JD2455197.5 = 2015-01-01T00:00:00

      • JD_J2015_5

        public static final double JD_J2015_5
        Julian date of the Gaia DR2 reference epoch, J2015.5 = JD2455197.5 = 2015-01-01T00:00:00

      • JD_J2010

        public static final double JD_J2010
        Julian date of TGAS epoch 2010-01-01T00:00:00

      • J2000_MS

        public static final long J2000_MS
        Milliseconds of J2000 in the scale of java.util.Date

    • Constructor Detail

      • AstroUtils

        public AstroUtils()

    • Method Detail

      • getJulianDate

        public static double getJulianDate​(double refEpoch)
        Get julian date from a double reference epoch
        Parameters:
        refEpoch - The reference epoch
        Returns:
        The julian date

      • getSunDistance

        public static double getSunDistance​(java.time.Instant date)
        Algorithm in "Astronomical Algorithms" book by Jean Meeus. Finds out the distance from the Sun to the Earth in Km
        Parameters:
        date - The date
        Returns:
        The distancee from the Sun to the Earth in Km

      • getSunDistance

        public static double getSunDistance​(double jd)

      • getSunLongitude

        public static double getSunLongitude​(java.time.Instant date)
        Returns the Sun's ecliptic longitude in degrees for the given time. Caches the last Sun's longitude for future use.
        Parameters:
        date - The time for which the longitude must be calculated
        Returns:
        The Sun's longitude in [deg]

      • getSunLongitudeWikipedia

        public static double getSunLongitudeWikipedia​(double jd)
        Gets the ecliptic longitude of the Sun in degrees as published in Wikipedia.
        Parameters:
        jd - The Julian date for which to calculate the latitude.
        Returns:
        The ecliptic longitude of the Sun at the given Julian date, in degrees.
        See Also:
        http://en.wikipedia.org/wiki/Position_of_the_Sun

      • moonEquatorialCoordinates

        public static void moonEquatorialCoordinates​(Vector3d placeholder,
                                             java.time.Instant date)
        Algorithm in "Astronomical Algorithms" book by Jean Meeus. Returns a vector with the equatorial longitude (α) in radians, the equatorial latitude (δ) in radians and the distance in kilometers.
        Parameters:
        date -

      • moonEquatorialCoordinates

        public static void moonEquatorialCoordinates​(Vector3d placeholder,
                                             double julianDate)
        Algorithm in "Astronomical Algorithms" book by Jean Meeus. Returns a vector with the equatorial longitude (α) in radians, the equatorial latitude (δ) in radians and the distance in kilometers.
        Parameters:
        julianDate -

      • moonEclipticCoordinates

        public static Vector3d moonEclipticCoordinates​(java.time.Instant date,
                                               Vector3d out)
        Algorithm in "Astronomical Algorithms" book by Jean Meeus. Returns a vector with the ecliptic longitude (λ) in radians, the ecliptic latitude (β) in radians and the distance in kilometers.
        Parameters:
        date -
        out - The output vector.
        Returns:
        The output vector, for chaining.

      • moonEclipticCoordinates

        public static Vector3d moonEclipticCoordinates​(double julianDate,
                                               Vector3d out)
        Algorithm in "Astronomical Algorithms" book by Jean Meeus. Returns a vector with the ecliptic longitude (λ) in radians, the ecliptic latitude (β) in radians and the distance between the centers of the Earth and the Moon in kilometers.
        Parameters:
        julianDate -
        out - The output vector with geocentric longitude (lambda) [rad], geocentric latitude (beta) [rad], distance between the centers of the Earth and the Moon [km]
        Returns:
        The output vector, for chaining.

      • plutoEclipticCoordinates

        public static Vector3d plutoEclipticCoordinates​(java.time.Instant date,
                                                Vector3d out)
        Ecliptic coordinates of pluto at the given date
        Parameters:
        date - The date
        out - The out vector
        Returns:
        Ecliptic coordinates of Pluto at the given julian date

      • plutoEclipticCoordinates

        public static Vector3d plutoEclipticCoordinates​(double d,
                                                Vector3d out)
        Ecliptic coordinates of pluto at the given date. See http://www.stjarnhimlen.se/comp/ppcomp.html
        Parameters:
        d - Julian date
        out - The out vector
        Returns:
        Ecliptic coordinates of Pluto at the given julian date

      • getEclipticCoordinates

        public static Vector3d getEclipticCoordinates​(java.lang.String body,
                                              java.time.Instant instant,
                                              Vector3d out,
                                              boolean highAccuracy)
        Returns a vector with the heliocentric ecliptic latitude and longitude in radians and the distance in internal units.
        Parameters:
        body - The body.
        instant - The date to get the position.
        out - The output vector
        highAccuracy - Whether to use the full precision algorithms or skip some terms for speed
        Returns:
        The output vector with L, B and R, for chaining.

      • getJulianDate

        public static double getJulianDate​(int year,
                                   int month,
                                   int day,
                                   int hour,
                                   int min,
                                   int sec,
                                   int nanos,
                                   boolean gregorian)
        Gets the Julian date number given the Gregorian calendar quantities.
        Parameters:
        year -
        month -
        day -
        hour -
        min -
        sec -
        nanos -
        gregorian - Whether to use the Gregorian or the Julian calendar
        Returns:
        The julian date number

      • getJulianDateCache

        public static double getJulianDateCache​(java.time.Instant instant)
        Gets the Julian Date for the given date. It uses a cache.
        Parameters:
        instant - The date.
        Returns:
        The Julian Date.

      • getJulianDate

        public static double getJulianDate​(java.time.Instant instant)

      • getMsSinceJ2010

        public static double getMsSinceJ2010​(java.time.Instant date)
        Returns the elapsed milliseconds since the epoch J2010 until the given date. Can be negavite.
        Parameters:
        date - The date
        Returns:
        The elapsed milliseconds

      • getMsSinceJ2000

        public static double getMsSinceJ2000​(java.time.Instant date)
        Returns the elapsed milliseconds since the epoch J2000 until the given date. Can be negavite.
        Parameters:
        date - The date
        Returns:
        The elapsed milliseconds

      • getDaysSinceJ2000

        public static double getDaysSinceJ2000​(java.time.Instant date)
        Returns the elapsed days since the epoch J2000 until the given date. Can be negavite.
        Parameters:
        date - The date
        Returns:
        The elapsed days

      • getMsSinceJ2015

        public static double getMsSinceJ2015​(java.time.Instant date)
        Returns the elapsed milliseconds since the epoch J2015 until the given date. Can be negavite.
        Parameters:
        date - The date
        Returns:
        The elapsed milliseconds

      • getMsSince

        public static double getMsSince​(java.time.Instant date,
                                double epoch_jd)
        Returns the elapsed milliseconds since the given julian date jd until the given date. Can be negative
        Parameters:
        date - The date
        epoch_jd - The reference epoch in julian days
        Returns:
        The elapsed milliseconds

      • getCalendarDay

        public static int[] getCalendarDay​(double julianDate)
        Gets the Gregorian calendar quantities given the Julian date.
        Parameters:
        julianDate - The Julian date
        Returns:
        Vector with {year, month, day, hour, min, sec, nanos}

      • getJulianDayNumberBook

        @Deprecated
public static double getJulianDayNumberBook​(int year,
                                            int month,
                                            int day)
        Deprecated.
        This does not work well!
        Returns the Julian day number. Uses the method shown in "Astronomical Algorithms" by Jean Meeus.
        Parameters:
        year - The year
        month - The month in [1:12]
        day - The day in the month, starting at 1
        Returns:
        The Julian date

      • getJulianDayNumberWikipediaGregorianCalendar

        public static double getJulianDayNumberWikipediaGregorianCalendar​(int year,
                                                                  int month,
                                                                  int day)
        Returns the Julian day number of a date in the Gregorian calendar. Uses Wikipedia's algorithm.
        Parameters:
        year - The year
        month - The month in [1:12]
        day - The day in the month, starting at 1
        Returns:
        The Julian date
        See Also:
        http://en.wikipedia.org/wiki/Julian_day

      • getJulianDayNumberWikipediaJulianCalendar

        public static double getJulianDayNumberWikipediaJulianCalendar​(int year,
                                                               int month,
                                                               int day)
        Returns the Julian day number of a date in the Julian calendar. Uses Wikipedia's algorithm.
        Parameters:
        year - The year
        month - The month in [1:12]
        day - The day in the month, starting at 1
        Returns:
        The Julian date
        See Also:
        http://en.wikipedia.org/wiki/Julian_day

      • julianDateToInstant

        public static java.time.Instant julianDateToInstant​(double jd)

      • getDayFraction

        public static double getDayFraction​(int hour,
                                    int min,
                                    int sec,
                                    int nanos)
        Gets the day fraction from the day quantities
        Parameters:
        hour - The hour in 0-24
        min - The minute in 0-1440
        sec - The second in 0-86400
        nanos - The nanoseconds
        Returns:
        The day fraction

      • getDayQuantities

        public static int[] getDayQuantities​(double dayFraction)
        Gets the day quantities from the day fraction
        Parameters:
        dayFraction -
        Returns:
        [hours, minutes, seconds, nanos]

      • obliquity

        public static double obliquity​(double julianDate)
        Returns the obliquity of the ecliptic (inclination of the Earth's axis of rotation) for a given date, in degrees
        Returns:
        The obliquity in degrees

      • T

        public static double T​(double julianDate)
        Time T measured in Julian centuries from the Epoch J2000.0
        Parameters:
        julianDate - The julian date
        Returns:
        The time in julian centuries

      • tau

        public static double tau​(double julianDate)

      • properMotionsToCartesian

        public static Vector3d properMotionsToCartesian​(double mualphastar,
                                                double mudelta,
                                                double radvel,
                                                double ra,
                                                double dec,
                                                double distpc)
        Converts proper motions + radial velocity into a cartesian vector. See this article.
        Parameters:
        mualphastar - Mu alpha star, in mas/yr
        mudelta - Mu delta, in mas/yr
        radvel - Radial velocity in km/s
        ra - Right ascension in radians
        dec - Declination in radians
        distpc - Distance in parsecs to the star
        Returns:
        The proper motion vector in internal_units/year