AstCoordinate.h

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#ifndef ASTCOORDINATE_H
#define ASTCOORDINATE_H

// AstCoordinate                          
//              
// Package: Ast (AstroUtil).
//                          
// Purpose: Provide utility routines to convert between different
//          astronomical coordinate sytems.
//
//          Horizon coordinates (altitude,azimuth) are defined as:
//          altitude:  elevation above the horizon, measured from -90^o (nadir)
//                     through 0^o (horizon) to +90^o (zenith).
//          azimuth:  the angle in the horizon plane measured easterly from
//                    north, i.e. 0^o is North, 90^o East, 180^o South,
//                    270^o West.
//
//          Local Det. Coordinate direction cosines (dcosx,dcosy,dcosz) are 
//          defined in the local coordinate system of a specified detector
//          type (Detector::Detector_t):
//          +z: horizontal component of the beam direction.
//          +y: local vertical.
//          +x: chosen to make coordinate system right-handed.
//
//          Ideal Det. Coordinate direction cosines (dcosx_ideal,dcosy_ideal,
//          dcosz_ideal) are defined such that:
//          +z: points North.
//          +y: radius vector originating at center of earth.
//          +x: points West.   
//
//          Geocentric Equatorial coordinates (hourangle, declination),
//          are defined relative to the earth's equatorial plane.
//          hourangle:  time since the object crossed the observer's meridian 
//                      (the great circle passing through the observer's zenith
//                       and the poles).  Measured from 0 to 360^o.
//          declination: elevation above the equatorial plane, measured from
//                       -90^o to 90^o.
//
//          Geocentric Celestial coordinates (right ascension,declination),
//          are defined as in the equatorial system, but instead of rotating
//          with the earth, they are fixed on the celestial sphere.
//          right ascension: angle in the equatorial plane measured eastwards
//                           from the rising of Aries. Measured from 0 - 360^o.
//          declination: same as for Geocentric Equatorial coordinates.
//
//          Geocentric Ecliptic coordinates (ecliptic latitude, beta, ecliptic 
//          longitude, lamda), are defined relative to the ecliptic great circle.
//          They are also fixed on the celestial sphere 
//          latitude: elevation over the ecliptic (-90 to 90^o).
//          longitude: angle in the ecliptic plane, measured eastwards from the 
//          rising of Aries (one of two points where the equatorial and ecliptic
//          circles cross).  

#include "Conventions/Detector.h"

namespace AstUtil {

  void LocalToIdeal(double dcosx, double dcosy, double dcosz,
                    Detector::Detector_t dettype, double& dcosx_ideal,
                    double& dcosy_ideal, double& dcosz_ideal);
  void IdealToLocal(double dcosx_ideal, double dcosy_ideal, double dcosz_ideal,
                    Detector::Detector_t dettype, double& dcosx,
                    double& dcosy, double& dcosz);
  void HorizonToLocal(double altitude, double azimuth, 
                      Detector::Detector_t dettype, double& dcosx,
                      double& dcosy, double& dcosz);
  void LocalToHorizon(double dcosx, double dcosy, double dcosz,
                      Detector::Detector_t dettype, double& altitude, 
                      double& azimuth);
  void HorizonToIdeal(double altitude, double azimuth,double& dcosx_ideal,
                      double& dcosy_ideal,double& dcosz_ideal);
  void IdealToHorizon(double dcosx_ideal, double dcosy_ideal, 
                      double dcosz_ideal,double& altitude, double& azimuth);
  void HorizonToEquatorial(double altitude, double azimuth, 
          double latitude, double& hourangle, double& declination);
  void EquatorialToHorizon(double hourangle, double declination, 
          double latitude, double& altitude, double& azimuth);
  void CelestialToEquatorial(double ra, double gmst, 
          double longitude, double& hourangle);
  void EquatorialToCelestial(double hourangle, double gmst, 
          double longitude, double& ra);
  void CelestialToEcliptic(double declination, double ra,
                double& beta, double& lamda);
  void EclipticToCelestial(double beta, double lamda,
                double& declination, double& ra);

}

#endif  // ASTCOORDINATE_H

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