To transform a star's catalog quantities for a change of epoch and/or equator and equinox.

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

Syntax

C#
public void TransformCat(
	TransformationOption option,
	double date_incat,
	ref CatEntry incat,
	double date_newcat,
	ref byte[] newcat_id,
	ref CatEntry newcat
)
Visual Basic
Public Sub TransformCat ( _
	option As TransformationOption, _
	date_incat As Double, _
	ByRef incat As CatEntry, _
	date_newcat As Double, _
	ByRef newcat_id As Byte(), _
	ByRef newcat As CatEntry _
)
Visual C++
public:
virtual void TransformCat(
	TransformationOption option, 
	double date_incat, 
	CatEntry% incat, 
	double date_newcat, 
	array<unsigned char>^% newcat_id, 
	CatEntry% newcat
) sealed

Parameters

option
Type: ASCOM.Astrometry..::..TransformationOption
Transformation option
    = 1 ... change epoch; same equator and equinox
    = 2 ... change equator and equinox; same epoch
    = 3 ... change equator and equinox and epoch
date_incat
Type: System..::..Double
TT Julian date, or year, of input catalog data.
incat
Type: ASCOM.Astrometry..::..CatEntry%
An entry from the input catalog
date_newcat
Type: System..::..Double
TT Julian date, or year, of transformed catalog data.
newcat_id
Type: array<System..::..Byte>[]()[][]%
Three-character abbreviated name of the transformed catalog.
newcat
Type: ASCOM.Astrometry..::..CatEntry%
OUT: The transformed catalog entry

Remarks

 1. 'date_incat' and 'date_newcat' may be specified either as a 
    Julian date (e.g., 2433282.5) or a Julian year and fraction 
    (e.g., 1950.0).  Values less than 10000 are assumed to be years.
 
 2. option = 1 updates the star's data to account for the star's space motion between 
               the first and second dates, within a fixed reference frame.
    option = 2 applies a rotation of the reference frame corresponding to precession 
               between the first and second dates, but leaves the star fixed in space.
    option = 3 provides both transformations.
 
 3. This subroutine cannot be properly used to bring data from 
    old (pre-FK5) star catalogs into the modern system, because old 
    catalogs were compiled using a set of constants that are 
    incompatible with the IAU (1976) system.
 
 4. This function uses TDB Julian dates internally, but no 
    distinction between TDB and TT is necessary.

See Also