Class SkyBox

java.lang.Object
uk.ac.starlink.ttools.cone.SkyBox

public class SkyBox extends 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

    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[]
    Returns declination range.
    double[]
    Returns right ascension range.
    Converts the units of this SkyBox from radians to degrees.
    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 Details

    • 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