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NOVAS2COMEqu2Hor Method
Transform apparent equatorial coordinates to horizon coordinates

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 tjd,
	double deltat,
	double x,
	double y,
	ref SiteInfo location,
	double ra,
	double dec,
	RefractionOption ref_option,
	ref double zd,
	ref double az,
	ref double rar,
	ref double decr
)

Parameters

tjd
Type: SystemDouble
TT (or TDT) Julian date.
deltat
Type: SystemDouble
Difference TT (or TDT)-UT1 at 'tjd', in seconds.
x
Type: SystemDouble
Conventionally-defined x coordinate of celestial ephemeris pole with respect to IERS reference pole, in arcseconds.
y
Type: SystemDouble
Conventionally-defined y coordinate of celestial ephemeris pole with respect to IERS reference pole, in arcseconds.
location
Type: ASCOM.AstrometrySiteInfo
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.
ref_option
Type: ASCOM.AstrometryRefractionOption
Refraction option
zd
Type: SystemDouble
OUT: Topocentric zenith distance in degrees, affected by refraction if 'ref_option' is non-zero.
az
Type: SystemDouble
OUT: Topocentric azimuth (measured east from north) in degrees.
rar
Type: SystemDouble
OUT: 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
OUT: 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 apparent equatorial coordinates (right ascension and declination) to horizon coordinates (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