Package uk.ac.starlink.ttools.cone
Class SkyBox
java.lang.Object
uk.ac.starlink.ttools.cone.SkyBox
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)
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
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Method Summary
Modifier and TypeMethodDescriptionstatic 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.
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Method Details
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getRaRange
public double[] getRaRange()Returns right ascension range. See class documentation for range semantics.- Returns:
- (ra1,ra2) array or null
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getDecRange
public double[] getDecRange()Returns declination range. See class documentation for range semantics.- Returns:
- (dec1,dec2) array or null
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toDegrees
Converts the units of this SkyBox from radians to degrees.- Returns:
- new sky box with converted range values
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toRadians
Converts the units of this SkyBox from degrees to radians.- Returns:
- new sky box with converted range values
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getConeBox
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 radiansdec
- cone centre declination in radianssr
- cone radius in radians- Returns:
- sky box enclosing cone, with angles in radians
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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 radianssr
- 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
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