Package skyview.geometry.csys
Class Julian
- java.lang.Object
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- skyview.geometry.CoordinateSystem
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- skyview.geometry.csys.Julian
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- All Implemented Interfaces:
java.io.Serializable
,Component
public class Julian extends CoordinateSystem implements Component
The class defining Julian coordinate systems. The reference coordinate system is J2000. We use the FK5 coordinate frame as the realization of the Julian coordinate system. At the 50 milliarcsecond level this is not valid: There is an offset of J2000 and FK5. However the details of this offset are still somewhat unclear, so we use the better defined frame.- See Also:
- Serialized Form
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Field Summary
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Fields inherited from class skyview.geometry.CoordinateSystem
B1950, Gal, ICRS, J2000
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Constructor Summary
Constructors Constructor Description Julian(double epoch)
Get a Julian CoordinateSystem of a given epoch.
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Method Summary
All Methods Instance Methods Concrete Methods Modifier and Type Method Description java.lang.String
getDescription()
Get a description of the object.java.lang.String
getName()
Get the name of this object.Rotater
getRotater()
Return the rotation associated with the coordinate system.Rotater
precession()
Get the Julian Precession Matrix for a given epoch (from J2000).-
Methods inherited from class skyview.geometry.CoordinateSystem
factory, factory, getSphereDistorter
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Method Detail
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getName
public java.lang.String getName()
Get the name of this object.
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getDescription
public java.lang.String getDescription()
Get a description of the object.- Specified by:
getDescription
in interfaceComponent
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getRotater
public Rotater getRotater()
Return the rotation associated with the coordinate system.- Specified by:
getRotater
in classCoordinateSystem
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precession
public Rotater precession()
Get the Julian Precession Matrix for a given epoch (from J2000). Approach based on P.Wallace's SLA library. The equations are available in Kaplan, USNO Circular 163, 1981, page A2. Here we assume in these equations we assume T=0 so that we are doing a transformation between J2000 and the specified ending epoch.
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