semidiameter

Documentation

Overview

Semidiameter: Chapter 55, Semidiameters of the Sun, Moon, and Planets.

Index

• Variables
• func Asteroid(d, Δ float64) unit.Angle
• func AsteroidDiameter(H, A float64) float64
• func MoonTopocentric(Δ float64, δ unit.Angle, H unit.HourAngle, ρsφʹ, ρcφʹ float64) float64
• func MoonTopocentric2(Δ float64, h unit.Angle) unit.Angle
• func SaturnApparentPolar(Δ float64, B unit.Angle) unit.Angle
• func Semidiameter(s0 unit.Angle, Δ float64) unit.Angle

Variables

var (
	Sun               = unit.AngleFromSec(959.63)
	Mercury           = unit.AngleFromSec(3.36)
	VenusSurface      = unit.AngleFromSec(8.34)
	VenusCloud        = unit.AngleFromSec(8.41)
	Mars              = unit.AngleFromSec(4.68)
	JupiterEquatorial = unit.AngleFromSec(98.44)
	JupiterPolar      = unit.AngleFromSec(92.06)
	SaturnEquatorial  = unit.AngleFromSec(82.73)
	SaturnPolar       = unit.AngleFromSec(73.82)
	Uranus            = unit.AngleFromSec(35.02)
	Neptune           = unit.AngleFromSec(33.50)
	Pluto             = unit.AngleFromSec(2.07)
	Moon              = unit.AngleFromSec(358473400 / base.AU)
)

Standard semidiameters at unit distance of 1 AU.

Functions

func Asteroid

func Asteroid(d, Δ float64) unit.Angle

Asteroid returns semidiameter of an asteroid with a given diameter at given distance.

Argument d is diameter in km, Δ is distance in AU.

Result is semidiameter.

func AsteroidDiameter

func AsteroidDiameter(H, A float64) float64

AsteroidDiameter returns approximate diameter given absolute magnitude H and albedo A.

Result is in km.

func MoonTopocentric

func MoonTopocentric(Δ float64, δ unit.Angle, H unit.HourAngle, ρsφʹ, ρcφʹ float64) float64

MoonTopocentric returns observed topocentric semidiameter of the Moon.

Δ is distance to Moon in AU.
δ is declination of Moon.
H is hour angle of Moon.
ρsφʹ, ρcφʹ are parallax constants as returned by
    globe.Ellipsoid.ParallaxConstants, for example.

func MoonTopocentric2

func MoonTopocentric2(Δ float64, h unit.Angle) unit.Angle

MoonTopocentric2 returns observed topocentric semidiameter of the Moon by a less rigorous method.

Δ is distance to Moon in AU, h is altitude of the Moon above the observer's horizon.

func SaturnApparentPolar

func SaturnApparentPolar(Δ float64, B unit.Angle) unit.Angle

SaturnApparentPolar returns apparent polar semidiameter of Saturn at specified distance.

Argument Δ must be observer-Saturn distance in AU. Argument B is Saturnicentric latitude of the observer as given by function saturnring.UB() for example.

func Semidiameter

func Semidiameter(s0 unit.Angle, Δ float64) unit.Angle

Semidiameter returns semidiameter at specified distance.

Δ must be observer-body distance in AU.