org.jscience.astronomy.solarsystem.coordinates.coordinatesystems
Class JulianCoordinateSystem

java.lang.Object
  extended by org.jscience.astronomy.solarsystem.coordinates.CoordinateSystem
      extended by org.jscience.astronomy.solarsystem.coordinates.coordinatesystems.JulianCoordinateSystem
All Implemented Interfaces:
Named

public class JulianCoordinateSystem
extends CoordinateSystem
implements Named

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.


Field Summary
 
Fields inherited from class org.jscience.astronomy.solarsystem.coordinates.CoordinateSystem
B1950, Galactic, ICRS, J2000
 
Constructor Summary
JulianCoordinateSystem(double epoch)
          Get a Julian CoordinateSystem of a given epoch.
 
Method Summary
 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 org.jscience.astronomy.solarsystem.coordinates.CoordinateSystem
factory, factory, getSphereDistorter
 
Methods inherited from class java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait
 

Constructor Detail

JulianCoordinateSystem

public JulianCoordinateSystem(double epoch)
Get a Julian CoordinateSystem of a given epoch.

Parameters:
epoch - The epoch of the equinox of the coordinates in calendar years (possibly fractional).
Method Detail

getName

public java.lang.String getName()
Get the name of this object.

Specified by:
getName in interface Named
Returns:
DOCUMENT ME!

getDescription

public java.lang.String getDescription()
Get a description of the object.


getRotater

public Rotater getRotater()
Return the rotation associated with the coordinate system.

Specified by:
getRotater in class CoordinateSystem

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.