com.askgeo.astronomy
Class TopocentricCoordinates

java.lang.Object
  com.askgeo.astronomy.TopocentricCoordinates

public class TopocentricCoordinates
extends java.lang.Object

The topocentric coordinates of an astronomical body are expressed in terms of an observer on the surface of the Earth at a given location at a given time. This object includes the azimuth (degrees), zenith (degrees), declination (degrees), right ascension (hours), and distance (astronomical units, AU).

The members of an instance are immutable and the constructor is not public. Instances of this class are returned by methods in the Earth class and can only be used by users in a read-only capacity.

The coordinates in this object may or may not include atmospheric refraction, depending on the parameters passed to the method that creates it. Please see the Earth class for more details.

Method Summary

double	getAzimuthDeg() The azimuth is an angular measurement in a spherical coordinate system that is calculated by perpendicularly projecting the vector from an observer (origin) to a point of interest onto a reference plane and measuring the angle between it and a reference vector on the reference plane (source: Wikipedia).
double	getDeclinationDeg() The declination is one of the two coordinates of the equatorial coordinate system, the other being either right ascension or hour angle.
double	getDistanceAu() The distance to the astronomical body is given in astronomical units (AU).
double	getRightAscensionHours() The right ascension is the astronomical term for one of the two direction coordinates of a point on the celestial sphere in the equatorial coordinate system, usually combined with declination.
double	getZenithDeg() The zenith (or "zenith angle") is the angle between the local "up" direction (opposite the gravity vector) and the astronomical body in question.

Methods inherited from class java.lang.Object

equals, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Method Detail

getAzimuthDeg

public double getAzimuthDeg()

The azimuth is an angular measurement in a spherical coordinate system that is calculated by perpendicularly projecting the vector from an observer (origin) to a point of interest onto a reference plane and measuring the angle between it and a reference vector on the reference plane (source: Wikipedia).

Returns:

the azimuth in degrees of an astronomical body at a particular time and from a particular location on the Earth.

getZenithDeg

public double getZenithDeg()

The zenith (or "zenith angle") is the angle between the local "up" direction (opposite the gravity vector) and the astronomical body in question. A body with a zenith angle of 90 degrees is at the horizon. A body with a zenith angle of 0 degrees is directly overhead.

Returns:

the zenith in degrees of an astronomical body at a particular time and from a particular location on the Earth.

getRightAscensionHours

public double getRightAscensionHours()

The right ascension is the astronomical term for one of the two direction coordinates of a point on the celestial sphere in the equatorial coordinate system, usually combined with declination. Right ascension's angular distance is measured eastward along the celestial equator from the vernal equinox to the hour circle of the point in question (from Wikipedia).

Returns:

the right ascension in hours of an astronomical body at a particular time.

getDeclinationDeg

public double getDeclinationDeg()

The declination is one of the two coordinates of the equatorial coordinate system, the other being either right ascension or hour angle. Declination in astronomy is comparable to geographic latitude, but projected onto the celestial sphere. Declination is measured in degrees north and south of the celestial equator. Points north of the celestial equator have positive declinations, while those to the south have negative declinations (from Wikipedia).

Returns:

the declination in degrees of an astronomical body at a particular time.

getDistanceAu

public double getDistanceAu()

The distance to the astronomical body is given in astronomical units (AU). For reference, one AU is approximately the means distance from the Sun to the Earth.

Returns:

the distance to the astronomical body is given in astronomical units (AU).