saturnring

Documentation

Overview

Saturnrings: Chapter 45, The Ring of Saturn

Index

• Constants
• func Ring(jde float64, earth, saturn *pp.V87Planet) (B, Bʹ, ΔU, P, aEdge, bEdge unit.Angle)
• func UB(jde float64, earth, saturn *pp.V87Planet) (ΔU, B unit.Angle)

Examples

• Ring

Constants

const (
	InnerEdgeOfOuter = .8801
	OuterEdgeOfInner = .8599
	InnerEdgeOfInner = .6650
	InnerEdgeOfDusky = .5486
)

Constants for scaling aEdge and bEdge.

Functions

func Ring

func Ring(jde float64, earth, saturn *pp.V87Planet) (B, Bʹ, ΔU, P, aEdge, bEdge unit.Angle)

Ring computes quantities of the ring of Saturn.

B  Saturnicentric latitude of the Earth referred to the plane of the ring.
Bʹ  Saturnicentric latitude of the Sun referred to the plane of the ring.
ΔU  Difference between Saturnicentric longitudes of the Sun and the Earth.
P  Geometric position angle of the northern semiminor axis of the ring.
aEdge  Major axis of the out edge of the outer ring.
bEdge  Minor axis of the out edge of the outer ring.

Example

// Example 45.a, p. 320
earth, err := pp.LoadPlanet(pp.Earth)
if err != nil {
	fmt.Println(err)
	return
}
saturn, err := pp.LoadPlanet(pp.Saturn)
if err != nil {
	fmt.Println(err)
	return
}
B, Bʹ, ΔU, P, a, b := saturnring.Ring(2448972.50068, earth, saturn)
fmt.Printf("B  = %.3f\n", B.Deg())
fmt.Printf("Bʹ = %.3f\n", Bʹ.Deg())
fmt.Printf("ΔU = %.3f\n", ΔU.Deg())
fmt.Printf("P  = %.3f\n", P.Deg())
fmt.Printf("a  = %.2d\n", sexa.FmtAngle(a))
fmt.Printf("b  = %.2d\n", sexa.FmtAngle(b))

Output:

B  = 16.442
Bʹ = 14.679
ΔU = 4.198
P  = 6.741
a  = 35″.87
b  = 10″.15

func UB

func UB(jde float64, earth, saturn *pp.V87Planet) (ΔU, B unit.Angle)

UB computes quantities required by illum.Saturn().

Same as ΔU and B returned by Ring(). Results in radians.