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NOVAS31CioBasis Method
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 (6.3.0.2839)
Syntax
public short CioBasis(
	double JdTdbEquionx,
	double RaCioEquionx,
	ReferenceSystem RefSys,
	Accuracy Accuracy,
	ref double x,
	ref double y,
	ref double z
)

Parameters

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

Return Value

Type: Int16
 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