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NOVAS31Equ2Hor Method
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 (6.3.0.2839)
Syntax
public void Equ2Hor(
	double Jd_Ut1,
	double DeltT,
	Accuracy Accuracy,
	double xp,
	double yp,
	OnSurface Location,
	double Ra,
	double Dec,
	RefractionOption RefOption,
	ref double Zd,
	ref double Az,
	ref double RaR,
	ref double DecR
)

Parameters

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