This function rotates a vector from the celestial to the terrestrial system. Specifically, it transforms a vector in the GCRS (a local space-fixed system) to the ITRS (a rotating earth-fixed system) by applying rotations for the GCRS-to-dynamical frame tie, precession, nutation, Earth rotation, and polar motion.

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

Syntax

C#
public short Cel2Ter(
	double JdHigh,
	double JdLow,
	double DeltaT,
	Method Method,
	Accuracy Accuracy,
	OutputVectorOption OutputOption,
	double xp,
	double yp,
	double[] VecT,
	ref double[] VecC
)
Visual Basic
Public Function Cel2Ter ( _
	JdHigh As Double, _
	JdLow As Double, _
	DeltaT As Double, _
	Method As Method, _
	Accuracy As Accuracy, _
	OutputOption As OutputVectorOption, _
	xp As Double, _
	yp As Double, _
	VecT As Double(), _
	ByRef VecC As Double() _
) As Short
Visual C++
public:
virtual short Cel2Ter(
	double JdHigh, 
	double JdLow, 
	double DeltaT, 
	Method Method, 
	Accuracy Accuracy, 
	OutputVectorOption OutputOption, 
	double xp, 
	double yp, 
	array<double>^ VecT, 
	array<double>^% VecC
) sealed

Parameters

JdHigh
Type: System..::..Double
High-order part of UT1 Julian date.
JdLow
Type: System..::..Double
Low-order part of UT1 Julian date.
DeltaT
Type: System..::..Double
Value of Delta T (= TT - UT1) at the input UT1 Julian date.
Method
Type: ASCOM.Astrometry..::..Method
Selection for method: 0 ... CIO-based method; 1 ... equinox-based method
Accuracy
Type: ASCOM.Astrometry..::..Accuracy
Selection for accuracy
OutputOption
Type: ASCOM.Astrometry..::..OutputVectorOption
0 ... The output vector is referred to GCRS axes; 1 ... The output vector is produced with respect to the equator and equinox of date. (See note 2 below)
xp
Type: System..::..Double
Conventionally-defined X coordinate of celestial intermediate pole with respect to ITRS pole, in arcseconds.
yp
Type: System..::..Double
Conventionally-defined Y coordinate of celestial intermediate pole with respect to ITRS pole, in arcseconds.
VecT
Type: array<System..::..Double>[]()[][]
Position vector, geocentric equatorial rectangular coordinates, referred to GCRS axes (celestial system) or with respect to the equator and equinox of date, depending on 'option'.
VecC
Type: array<System..::..Double>[]()[][]%
Position vector, geocentric equatorial rectangular coordinates, referred to ITRS axes (terrestrial system).

Return Value

    0 ... everything is ok
    1 ... invalid value of 'Accuracy'
    2 ... invalid value of 'Method'
 > 10 ... 10 + error from function 'CioLocation'
 > 20 ... 20 + error from function 'CioBasis'
 

Remarks

Note 1: 'x' = 'y' = 0 means no polar motion transformation.

Note2: 'option' = 1 only works for the equinox-based method.

See Also