solarxyz

Documentation

Overview

Solarxyz: Chapter 26, Rectangular Coordinates of the Sun.

Index

• func LongitudeJ2000(e *pp.V87Planet, jde float64) (l unit.Angle)
• func Position(e *pp.V87Planet, jde float64) (x, y, z float64)
• func PositionB1950(e *pp.V87Planet, jde float64) (x, y, z float64)
• func PositionEquinox(e *pp.V87Planet, jde, epoch float64) (xp, yp, zp float64)
• func PositionJ2000(e *pp.V87Planet, jde float64) (x, y, z float64)

Examples

• Position
• PositionB1950
• PositionEquinox
• PositionJ2000

Functions

func LongitudeJ2000

func LongitudeJ2000(e *pp.V87Planet, jde float64) (l unit.Angle)

LongitudeJ2000 returns geometric longitude referenced to equinox J2000. J2000太阳地心黄经

func Position

func Position(e *pp.V87Planet, jde float64) (x, y, z float64)

Position returns rectangular coordinates referenced to the mean equinox of date. Date 平分点太阳地心直角坐标

Example

package main

import (
	"fmt"

	pp "github.com/mooncaker816/learnmeeus/v3/planetposition"
	"github.com/mooncaker816/learnmeeus/v3/solarxyz"
)

func main() {
	// Example 26.a, p. 172.
	e, err := pp.LoadPlanet(pp.Earth)
	if err != nil {
		fmt.Println(err)
		return
	}
	x, y, z := solarxyz.Position(e, 2448908.5)
	fmt.Printf("X = %.7f\n", x)
	fmt.Printf("Y = %.7f\n", y)
	fmt.Printf("Z = %.7f\n", z)
	// Meeus result (using appendix III):
	// X = -0.9379952
	// Y = -0.3116544
	// Z = -0.1351215

}

Output:

X = -0.9379963
Y = -0.3116537
Z = -0.1351207

func PositionB1950

func PositionB1950(e *pp.V87Planet, jde float64) (x, y, z float64)

PositionB1950 returns rectangular coordinates referenced to B1950. B1950 平分点参考系太阳直角坐标

Results are referenced to the mean equator and equinox of the epoch B1950 in the FK5 system, not FK4.

Example

package main

import (
	"fmt"

	pp "github.com/mooncaker816/learnmeeus/v3/planetposition"
	"github.com/mooncaker816/learnmeeus/v3/solarxyz"
)

func main() {
	// Example 26.b, p. 175
	e, err := pp.LoadPlanet(pp.Earth)
	if err != nil {
		fmt.Println(err)
		return
	}
	x, y, z := solarxyz.PositionB1950(e, 2448908.5)
	fmt.Printf("X0 = %.8f\n", x)
	fmt.Printf("Y0 = %.8f\n", y)
	fmt.Printf("Z0 = %.8f\n", z)
}

Output:

X0 = -0.94148805
Y0 = -0.30266488
Z0 = -0.13121349

func PositionEquinox

func PositionEquinox(e *pp.V87Planet, jde, epoch float64) (xp, yp, zp float64)

PositionEquinox returns rectangular coordinates referenced to an arbitrary epoch. 任意其它平分点参考系太阳直角坐标

Position will be computed for given Julian day "jde" but referenced to mean equinox "epoch" (year).

Example

package main

import (
	"fmt"

	pp "github.com/mooncaker816/learnmeeus/v3/planetposition"
	"github.com/mooncaker816/learnmeeus/v3/solarxyz"
)

func main() {
	// Example 26.b, p. 175
	e, err := pp.LoadPlanet(pp.Earth)
	if err != nil {
		fmt.Println(err)
		return
	}
	x, y, z := solarxyz.PositionEquinox(e, 2448908.5, 2044)
	fmt.Printf("X0 = %.8f\n", x)
	fmt.Printf("Y0 = %.8f\n", y)
	fmt.Printf("Z0 = %.8f\n", z)
}

Output:

X0 = -0.93368100
Y0 = -0.32237347
Z0 = -0.13977803

func PositionJ2000

func PositionJ2000(e *pp.V87Planet, jde float64) (x, y, z float64)

PositionJ2000 returns rectangular coordinates referenced to equinox J2000. J2000太阳直角坐标

Example

package main

import (
	"fmt"

	pp "github.com/mooncaker816/learnmeeus/v3/planetposition"
	"github.com/mooncaker816/learnmeeus/v3/solarxyz"
)

func main() {
	// Example 26.b, p. 175 but for output see complete VSOP87
	// results given on p. 176.
	e, err := pp.LoadPlanet(pp.Earth)
	if err != nil {
		fmt.Println(err)
		return
	}
	x, y, z := solarxyz.PositionJ2000(e, 2448908.5)
	fmt.Printf("X0 = %.8f\n", x)
	fmt.Printf("Y0 = %.8f\n", y)
	fmt.Printf("Z0 = %.8f\n", z)
}

Output:

X0 = -0.93739707
Y0 = -0.31316724
Z0 = -0.13577841