SOFA Class

This class presents a subset of the SOFA (Standards of Fundamental Astronomy) astrometry routines in a form that is easily accessible from both 32bit and 64bit .NET and COM applications.

Inheritance Hierarchy

SystemObject
ASCOM.Astrometry.SOFASOFA

Namespace: ASCOM.Astrometry.SOFA
Assembly: ASCOM.Astrometry (in ASCOM.Astrometry.dll) Version: 6.0.0.0 (6.6.9999.9999)

Syntax

C++

Copy

public class SOFA : IDisposable

Public Class SOFA
	Implements IDisposable

public ref class SOFA : IDisposable

The SOFA type exposes the following members.

Constructors

	Name	Description
	SOFA	Creates a new instance of the SOFA component

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Methods

	Name	Description
	Af2a	Convert degrees, arcminutes, arcseconds to radians.
	Anp	Normalize angle into the range 0 <= a < 2pi.
	CelestialToIntermediate	Transform ICRS star data, epoch J2000.0, to CIRS using the SOFA Atci13 function.
	CelestialToObserved	ICRS RA,Dec to observed place using the SOFA Atco13 function.
	Dispose	Cleans up the SOFA object
	Dtf2d	Encode date and time fields into 2-part Julian Date (or in the case of UTC a quasi-JD form that includes special provision for leap seconds).
	Eo06a	Equation of the origins, IAU 2006 precession and IAU 2000A nutation.
	Hd2ae	Transform hour angle and declination to azimuth And altitude.
	IntermediateToCelestial	Transform star RA,Dec from geocentric CIRS to ICRS astrometric using the SOFA Atic13 function.
	IntermediateToObserved	CIRS RA,Dec to observed place using the SOFA Atio13 funciton.
	Ir	Initialize an r−matrix to the identity matrix.
	ObservedToCelestial	Observed place at a groundbased site to to ICRS astrometric RA,Dec using the SOFA Atoc13 function.
	ObservedToIntermediate	Observed place to CIRS using the SOFA Atoi13 function.
	Pv2s	Convert position/velocity from Cartesian to spherical coordinates.
	Rxpv	Multiply a pv−vector by an r−matrix.
	Ry	Rotate an r−matrix about the y−axis.
	S2pv	Convert position/velocity from spherical to Cartesian coordinates.
	SofaIssueDate	Release date of the SOFA issue currently used by this component.
	SofaReleaseNumber	Major number of the SOFA issue currently used by this component.
	SofaRevisionDate	Release date of the revision to the SOFA Issue that is actually being used by this component.
	TaiTt	Time scale transformation: International Atomic Time, TAI, to Terrestrial Time, TT.
	TaiUtc	Time scale transformation: International Atomic Time, TAI, to Coordinated Universal Time, UTC.
	Tf2a	Convert hours, minutes, seconds to radians.
	TtTai	Time scale transformation: Terrestrial Time, TT, to International Atomic Time, TAI.
	UtcTai	Time scale transformation: Coordinated Universal Time, UTC, to International Atomic Time, TAI.

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Remarks

SOFA operates under the auspices of the International Astronomical Union (IAU) to provide algorithms and software for use in astronomical computing. The entire SOFA collection comprises many authoritative routines across a number of areas including:

Astrometry
Calendars
Time Scales
Earth rotation and sidereal time
Ephemerides (medium precision)
Geocentric/geodetic transformations
Precession, nutation, polar motion
Star space motion
Star catalogue conversion

The class's functionality is provided by underlying DLLs compiled from unmodified original C source code distributed by SOFA but the class does not constitute software provided by and/or endorsed by SOFA. No change whatsoever has been made to the algorithms implemented by SOFA that realise IAU standards.

SOFA provides a validation routine to confirm that the compiled library provides expected results. 32 and 64bit versions of this routine (SofaTestXX.exe and SofaTestXX-64.exe, where XX is the issue number) are included in this distribution and can be found in the Common Files\ASCOM\Astrometry directory. To run them open a command prompt in the Astrometry directory and enter the commands SofaTest10 /verbose and SofaTest10-64 /verbose. The susbset of these tests that is relevant to the routines presented in this component have also been incorporated in the ASCOM Diagnostics tool and expected operation of the SOFA routnines can be confirmed through this tool.

Further information on the full library of SOFA routines is available here: http://www.iausofa.org/

Reference

ASCOM.Astrometry.SOFA Namespace