Determines the angle of an object above or below the Earth's limb (horizon).

Namespace: ASCOM.Astrometry.NOVAS
Assembly: ASCOM.Astrometry (in ASCOM.Astrometry.dll) Version: 6.0.0.0 (6.1.1.2619)

Syntax

C#
public void LimbAngle(
	double[] PosObj,
	double[] PosObs,
	ref double LimbAng,
	ref double NadirAng
)
Visual Basic
Public Sub LimbAngle ( _
	PosObj As Double(), _
	PosObs As Double(), _
	ByRef LimbAng As Double, _
	ByRef NadirAng As Double _
)
Visual C++
public:
virtual void LimbAngle(
	array<double>^ PosObj, 
	array<double>^ PosObs, 
	double% LimbAng, 
	double% NadirAng
) sealed

Parameters

PosObj
Type: array<System..::..Double>[]()[][]
Position vector of observed object, with respect to origin at geocenter, components in AU.
PosObs
Type: array<System..::..Double>[]()[][]
Position vector of observer, with respect to origin at geocenter, components in AU.
LimbAng
Type: System..::..Double%
Angle of observed object above (+) or below (-) limb in degrees.
NadirAng
Type: System..::..Double%
Nadir angle of observed object as a fraction of apparent radius of limb: < 1.0 ... below the limb; = 1.0 ... on the limb; > 1.0 ... above the limb

Remarks

The geometric limb is computed, assuming the Earth to be an airless sphere (no refraction or oblateness is included). The observer can be on or above the Earth. For an observer on the surface of the Earth, this function returns the approximate unrefracted altitude.

See Also