Class SkyBox


  • public class SkyBox
    extends java.lang.Object
    Defines a region of the celestial sphere which is rectangular in Right Ascension and Declination coordinates.

    This class just aggregates a two-element double[] array (x1,x2) for each of right ascension and declination. The meaning in each case is as follows:

    • x1<x2: included range (x1 <= value <= x2)
    • x1>x2: excluded range (value <= x1 or value >= x2)
    The degenerate case x1==x2 can be viewed as either.

    Values should be in the range 0<=ra<2*PI and -PI/2<dec<+PI (or equivalent in degrees if degrees are being used).

    The static getConeBox(double, double, double) method is provided to generate a SkyBox suitable for cone search queries.

    Since:
    9 Jan 2008
    Author:
    Mark Taylor
    • Method Summary

      All Methods Static Methods Instance Methods Concrete Methods 
      Modifier and Type Method Description
      static double calculateDeltaRa​(double dec, double sr)
      Works out the minimum change in Right Ascension which will encompass all points within a given search radius at a given central declination.
      static SkyBox getConeBox​(double ra, double dec, double sr)
      Returns a minimal SkyBox which encloses a given cone using radians.
      double[] getDecRange()
      Returns declination range.
      double[] getRaRange()
      Returns right ascension range.
      SkyBox toDegrees()
      Converts the units of this SkyBox from radians to degrees.
      SkyBox toRadians()
      Converts the units of this SkyBox from degrees to radians.
      • Methods inherited from class java.lang.Object

        clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait
    • Method Detail

      • getRaRange

        public double[] getRaRange()
        Returns right ascension range. See class documentation for range semantics.
        Returns:
        (ra1,ra2) array or null
      • getDecRange

        public double[] getDecRange()
        Returns declination range. See class documentation for range semantics.
        Returns:
        (dec1,dec2) array or null
      • toDegrees

        public SkyBox toDegrees()
        Converts the units of this SkyBox from radians to degrees.
        Returns:
        new sky box with converted range values
      • toRadians

        public SkyBox toRadians()
        Converts the units of this SkyBox from degrees to radians.
        Returns:
        new sky box with converted range values
      • getConeBox

        public static SkyBox getConeBox​(double ra,
                                        double dec,
                                        double sr)
        Returns a minimal SkyBox which encloses a given cone using radians. The declination range of the result will be of included type, but the right ascension range may be either included or excluded.
        Parameters:
        ra - cone centre right ascension in radians
        dec - cone centre declination in radians
        sr - cone radius in radians
        Returns:
        sky box enclosing cone, with angles in radians
      • calculateDeltaRa

        public static double calculateDeltaRa​(double dec,
                                              double sr)
        Works out the minimum change in Right Ascension which will encompass all points within a given search radius at a given central declination.
        Parameters:
        dec - declination of the centre of the search region in radians
        sr - radius of the search region in radians
        Returns:
        minimum change in radians of RA from the central value which will contain the entire search region