ASCOM Library
NovasCio
Compute the orthonormal basis vectors of the celestial intermediate system.
Definition
Namespace: ASCOM.Tools.Novas31
Assembly: ASCOM.AstrometryTools (in ASCOM.AstrometryTools.dll) Version: 3.0.0-rc.1+86c25ce733aebb4d8b1b8a62e84770ea5e972bea
Assembly: ASCOM.AstrometryTools (in ASCOM.AstrometryTools.dll) Version: 3.0.0-rc.1+86c25ce733aebb4d8b1b8a62e84770ea5e972bea
C#
public static short CioBasis(
double JdTdbEquionx,
double RaCioEquionx,
ReferenceSystem RefSys,
Accuracy Accuracy,
ref double x,
ref double y,
ref double z
)VB
Public Shared 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 ShortParameters
- JdTdbEquionx Double
- TDB Julian date of epoch.
- RaCioEquionx Double
- Right ascension of the CIO at epoch (hours).
- RefSys ReferenceSystem
- Reference system in which right ascension is given. 1 ... GCRS; 2 ... True equator and equinox of date.
- Accuracy Accuracy
- Accuracy
- x Double
- Unit vector toward the CIO, equatorial rectangular coordinates, referred to the GCRS.
- y Double
- Unit vector toward the y-direction, equatorial rectangular coordinates, referred to the GCRS.
- z Double
- Unit vector toward north celestial pole (CIP), equatorial rectangular coordinates, referred to the GCRS.
Return Value
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.