Compute the orthonormal basis vectors of the celestial intermediate system.

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

Syntax

C#
public short CioBasis(
	double JdTdbEquionx,
	double RaCioEquionx,
	ReferenceSystem RefSys,
	Accuracy Accuracy,
	ref double x,
	ref double y,
	ref double z
)
Visual Basic
Public Function CioBasis ( _
	JdTdbEquionx As Double, _
	RaCioEquionx As Double, _
	RefSys As ReferenceSystem, _
	Accuracy As Accuracy, _
	ByRef x As Double, _
	ByRef y As Double, _
	ByRef z As Double _
) As Short
Visual C++
public:
virtual short CioBasis(
	double JdTdbEquionx, 
	double RaCioEquionx, 
	ReferenceSystem RefSys, 
	Accuracy Accuracy, 
	double% x, 
	double% y, 
	double% z
) sealed

Parameters

JdTdbEquionx
Type: System..::..Double
TDB Julian date of epoch.
RaCioEquionx
Type: System..::..Double
Right ascension of the CIO at epoch (hours).
RefSys
Type: ASCOM.Astrometry..::..ReferenceSystem
Reference system in which right ascension is given. 1 ... GCRS; 2 ... True equator and equinox of date.
Accuracy
Type: ASCOM.Astrometry..::..Accuracy
Accuracy
x
Type: System..::..Double%
Unit vector toward the CIO, equatorial rectangular coordinates, referred to the GCRS.
y
Type: System..::..Double%
Unit vector toward the y-direction, equatorial rectangular coordinates, referred to the GCRS.
z
Type: System..::..Double%
Unit vector toward north celestial pole (CIP), equatorial rectangular coordinates, referred to the GCRS.

Return Value

 0 ... everything OK
 1 ... invalid value of input variable 'RefSys'.
 

Remarks

To compute the orthonormal basis vectors, with respect to the GCRS (geocentric ICRS), of the celestial intermediate system defined by the celestial intermediate pole (CIP) (in the z direction) and the celestial intermediate origin (CIO) (in the x direction). A TDB Julian date and the right ascension of the CIO at that date is required as input. The right ascension of the CIO can be with respect to either the GCRS origin or the true equinox of date -- different algorithms are used in the two cases.

See Also