casacore::SolarPos Class Reference

Solar position class and calculations. More...

#include <SolarPos.h>

Public Types
enum	SolarPosTypes {   STANDARD,   NONE }
	Types of known SolarPos calculations (at 1995/09/04 STANDARD == IAU1980) More...

Public Member Functions
	SolarPos ()
	Default constructor, generates default J2000 SolarPos identification. More...
	SolarPos (const SolarPos &other)
	Copy constructor. More...
	SolarPos (SolarPosTypes type)
	Constructor with type. More...
SolarPos &	operator= (const SolarPos &other)
	Copy assignment. More...
	~SolarPos ()
const MVPosition &	operator() (Double epoch)
	Operator () calculates the geocentric Solar Position in AU. More...
const MVPosition &	derivative (Double epoch)
	Return derivatives of SolarPos (d-1) More...
const MVPosition &	baryEarthDerivative (Double epoch)
const MVPosition &	barySunDerivative (Double epoch)
const MVPosition &	baryEarth (Double epoch)
	Barycentric position of Earth. More...
const MVPosition &	barySun (Double epoch)
	Barycentric position of Sun. More...
void	init ()
	Re-initialise SolarPos object. More...
void	init (SolarPosTypes type)
void	refresh ()
	Refresh calculations. More...

Static Public Attributes
static const Double	INTV
	Interval to be used for linear approximation (in days) More...

Private Member Functions
void	copy (const SolarPos &other)
	Copy. More...
void	fill ()
	Fill an empty copy. More...
void	calcEarth (Double t)
	Calculate heliocentric Earth position for time t. More...
void	calcSun (Double t)
	Calculate heliocentric barycentre position. More...

Private Attributes
SolarPosTypes	method
	Method to be used. More...
Double	checkEpoch
	Check epoch for linear approximation. More...
Double	checkSunEpoch
Double	eval [3]
	Cached calculated Earth positions. More...
Double	deval [3]
	Cached derivatives. More...
Double	sval [3]
	Cached calculated Sun positions. More...
Double	dsval [3]
	Cached derivatives. More...
Int	lres
	To be able to use references in simple calculations, results are calculated in a circular buffer. More...
MVPosition	result [6]
	Last calculation. More...

Static Private Attributes
static uInt	interval_reg
	Interpolation interval. More...
static uInt	usejpl_reg
	JPL use. More...

Detailed Description

Solar position class and calculations.

Intended use:

Public interface

Review Status

Reviewed By:

UNKNOWN

Date Reviewed:

before2004/08/25

Test programs:

tMeasMath

Prerequisite

• Measure class, especially MEpoch
• MeasData class for constants

Etymology

SolarPos from Solar Position

Synopsis

SolarPos forms the class for Solar Position calculations. It is a simple container with the selected method, and the mean epoch.
The method is selected from one of the following:

• SolarPos::STANDARD (at 1995/09/04 the IAU1980 definition)
• SolarPos::NONE

Epochs can be specified as the MJD (with defined constants MeasData::MJD2000 and MeasData::MJDB1950 or the actual MJD), leading to the following constructors:

• SolarPos() default; assuming JD2000, IAU1980
• SolarPos(method) assuming the correct default epoch of JD2000
• SolarPos(method,epoch) with epoch Double(MJD)

Actual SolarPos for a certain Epoch is calculated by the () operator as SolarPos(epoch), with epoch Double MJD, as an MVPosition vector.
It returns the geocentric position of the heliocentre in rectangular coordinates in AU.
The derivative (d^-1) can be obtained as well by derivative(epoch), baryEarthDerivative() and barySunDerivative().
The Earth's and solar barycentric position can be obtained by the members baryEarth and barySun. The following details can be set with the Aipsrc mechanism:

• measures.solarpos.d_interval: approximation interval as time (fraction of days is default unit) over which linear approximation is used
• measures.solarpos.b_usejpl: use the JPL database for solar position. Else analytical expression, relative error about 10^-9 Note that the JPL database to be used can be set with measures.jpl.ephemeris (at the moment of writing DE200 (default), or DE405)

Reference: M. Soma et al., Cel. Mech. 41 (1988), 389; E.M. Standish, Astron. Astroph. 114 (1982), 297.

Example

Motivation

To calculate the solar/Earth positions for gravitational deflection. An alternate route could have been a global function, but having a simple container allows caching of some calculations for speed.
Using MJD (JD-2400000.5) rather than JD is for precision reasons.

Definition at line 111 of file SolarPos.h.

Member Enumeration Documentation

enum casacore::SolarPos::SolarPosTypes

Types of known SolarPos calculations (at 1995/09/04 STANDARD == IAU1980)

Enumerator
STANDARD
NONE

Definition at line 119 of file SolarPos.h.

Constructor & Destructor Documentation

casacore::SolarPos::SolarPos

(

)

Default constructor, generates default J2000 SolarPos identification.

casacore::SolarPos::SolarPos

(

const SolarPos &

other

)

Copy constructor.

casacore::SolarPos::SolarPos

(

SolarPosTypes

type

)

Constructor with type.

casacore::SolarPos::~SolarPos

(

)

Member Function Documentation

const MVPosition& casacore::SolarPos::baryEarth

(

Double

epoch

)

Barycentric position of Earth.

const MVPosition& casacore::SolarPos::baryEarthDerivative

(

Double

epoch

)

const MVPosition& casacore::SolarPos::barySun

(

Double

epoch

)

Barycentric position of Sun.

const MVPosition& casacore::SolarPos::barySunDerivative

(

Double

epoch

)

void casacore::SolarPos::calcEarth ( Double  t )

private

Calculate heliocentric Earth position for time t.

void casacore::SolarPos::calcSun ( Double  t )

private

Calculate heliocentric barycentre position.

void casacore::SolarPos::copy ( const SolarPos &  other )

private

Copy.

const MVPosition& casacore::SolarPos::derivative

(

Double

epoch

)

Return derivatives of SolarPos (d^-1)

void casacore::SolarPos::fill ( )

private

Fill an empty copy.

void casacore::SolarPos::init

(

)

Re-initialise SolarPos object.

void casacore::SolarPos::init

(

SolarPosTypes

type

)

const MVPosition& casacore::SolarPos::operator()

(

Double

epoch

)

Operator () calculates the geocentric Solar Position in AU.

SolarPos& casacore::SolarPos::operator=

(

const SolarPos &

other

)

Copy assignment.

void casacore::SolarPos::refresh

(

)

Refresh calculations.

Member Data Documentation

Double casacore::SolarPos::checkEpoch

private

Check epoch for linear approximation.

Definition at line 164 of file SolarPos.h.

Double casacore::SolarPos::checkSunEpoch

private

Definition at line 165 of file SolarPos.h.

Double casacore::SolarPos::deval[3]

private

Cached derivatives.

Definition at line 169 of file SolarPos.h.

Double casacore::SolarPos::dsval[3]

private

Cached derivatives.

Definition at line 173 of file SolarPos.h.

Double casacore::SolarPos::eval[3]

private

Cached calculated Earth positions.

Definition at line 167 of file SolarPos.h.

uInt casacore::SolarPos::interval_reg

staticprivate

Interpolation interval.

Definition at line 181 of file SolarPos.h.

const Double casacore::SolarPos::INTV

static

Interval to be used for linear approximation (in days)

Definition at line 115 of file SolarPos.h.

Int casacore::SolarPos::lres

private

To be able to use references in simple calculations, results are calculated in a circular buffer.

Current buffer pointer

Definition at line 177 of file SolarPos.h.

SolarPosTypes casacore::SolarPos::method

private

Method to be used.

Definition at line 162 of file SolarPos.h.

MVPosition casacore::SolarPos::result[6]

private

Last calculation.

Definition at line 179 of file SolarPos.h.

Double casacore::SolarPos::sval[3]

private

Cached calculated Sun positions.

Definition at line 171 of file SolarPos.h.

uInt casacore::SolarPos::usejpl_reg

staticprivate

JPL use.

Definition at line 183 of file SolarPos.h.

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The documentation for this class was generated from the following file:

• casa/casacore/measures/Measures/SolarPos.h