Package gaiasky.util.coord

Class AstroUtils

java.lang.Object
gaiasky.util.coord.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

    Modifier and Type Method Description
    static long[] 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 long[] getDayQuantities​(double dayFraction)
    Gets the day quantities from the day fraction
    static double getDaysSince​(java.time.Instant date, double epoch_jd)
    Returns the elapsed days since the given julian date jd until the given date.
    static double getDaysSinceJ2000​(java.time.Instant date)
    Returns the elapsed days since the epoch J2000 until the given date.
    static Vector3b getEclipticCoordinates​(java.lang.String body, java.time.Instant instant, Vector3b 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 Vector3b moonEclipticCoordinates​(java.time.Instant date, Vector3b 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 Vector3b plutoEclipticCoordinates​(java.time.Instant date, Vector3b out)
    Ecliptic coordinates of pluto at the given date
    static Vector3d properMotionsToCartesian​(double mualphastar, double mudelta, double radvel, double ra, double dec, double distpc, Vector3d out)
    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 Details

    • 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 Details

    • AstroUtils

      public AstroUtils()

  • Method Details

    • 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 Vector3b moonEclipticCoordinates​(java.time.Instant date, Vector3b 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 Vector3b plutoEclipticCoordinates​(java.time.Instant date, Vector3b 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

    • getEclipticCoordinates

      public static Vector3b getEclipticCoordinates​(java.lang.String body, java.time.Instant instant, Vector3b 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

    • getDaysSince

      public static double getDaysSince​(java.time.Instant date, double epoch_jd)
      Returns the elapsed days 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 days

    • getCalendarDay

      public static long[] 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 long[] 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, Vector3d out)
      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