Transforms topocentric right ascension and declination to zenith distance and azimuth.

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

Syntax

C#
public void Equ2Hor(
	double Jd_Ut1,
	double DeltT,
	Accuracy Accuracy,
	double x,
	double y,
	OnSurface Location,
	double Ra,
	double Dec,
	RefractionOption RefOption,
	ref double Zd,
	ref double Az,
	ref double RaR,
	ref double DecR
)
Visual Basic
Public Sub Equ2Hor ( _
	Jd_Ut1 As Double, _
	DeltT As Double, _
	Accuracy As Accuracy, _
	x As Double, _
	y As Double, _
	Location As OnSurface, _
	Ra As Double, _
	Dec As Double, _
	RefOption As RefractionOption, _
	ByRef Zd As Double, _
	ByRef Az As Double, _
	ByRef RaR As Double, _
	ByRef DecR As Double _
)
Visual C++
public:
virtual void Equ2Hor(
	double Jd_Ut1, 
	double DeltT, 
	Accuracy Accuracy, 
	double x, 
	double y, 
	OnSurface Location, 
	double Ra, 
	double Dec, 
	RefractionOption RefOption, 
	double% Zd, 
	double% Az, 
	double% RaR, 
	double% DecR
) sealed

Parameters

Jd_Ut1
Type: System..::..Double
UT1 Julian date.
DeltT
Type: System..::..Double
Difference TT-UT1 at 'jd_ut1', in seconds.
Accuracy
Type: ASCOM.Astrometry..::..Accuracy
Selection for accuracy
x
Type: System..::..Double
onventionally-defined x coordinate of celestial intermediate pole with respect to ITRS reference pole, in arcseconds.
y
Type: System..::..Double
Conventionally-defined y coordinate of celestial intermediate pole with respect to ITRS reference pole, in arcseconds.
Location
Type: ASCOM.Astrometry..::..OnSurface
Structure containing observer's location
Ra
Type: System..::..Double
Topocentric right ascension of object of interest, in hours, referred to true equator and equinox of date.
Dec
Type: System..::..Double
Topocentric declination of object of interest, in degrees, referred to true equator and equinox of date.
RefOption
Type: ASCOM.Astrometry..::..RefractionOption
Refraction option. 0 ... no refraction; 1 ... include refraction, using 'standard' atmospheric conditions; 2 ... include refraction, using atmospheric parametersinput in the 'Location' structure.
Zd
Type: System..::..Double%
Topocentric zenith distance in degrees, affected by refraction if 'ref_option' is non-zero.
Az
Type: System..::..Double%
Topocentric azimuth (measured east from north) in degrees.
RaR
Type: System..::..Double%
Topocentric right ascension of object of interest, in hours, referred to true equator and equinox of date, affected by refraction if 'ref_option' is non-zero.
DecR
Type: System..::..Double%
Topocentric declination of object of interest, in degrees, referred to true equator and equinox of date, affected by refraction if 'ref_option' is non-zero.

Remarks

This function transforms topocentric right ascension and declination to zenith distance and azimuth. It uses a method that properly accounts for polar motion, which is significant at the sub-arcsecond level. This function can also adjust coordinates for atmospheric refraction.

See Also