func ExampleApproxTimes() {
// Example 15.a, p. 103.
jd := julian.CalendarGregorianToJD(1988, 3, 20)
p := globe.Coord{
Lon: base.NewAngle(false, 71, 5, 0).Rad(),
Lat: base.NewAngle(false, 42, 20, 0).Rad(),
}
// Meeus gives us the value of 11h 50m 58.1s but we have a package
// function for this:
Th0 := sidereal.Apparent0UT(jd)
α := base.NewRA(2, 46, 55.51).Rad()
δ := base.NewAngle(false, 18, 26, 27.3).Rad()
h0 := rise.Stdh0Stellar
rise, transit, set, err := rise.ApproxTimes(p, h0, Th0, α, δ)
if err != nil {
fmt.Println(err)
return
}
// Units for approximate values given near top of p. 104 are circles.
fmt.Printf("rising: %+.5f\n", rise/86400)
fmt.Printf("transit: %+.5f\n", transit/86400)
fmt.Printf("seting: %+.5f\n", set/86400)
// Output:
// rising: +0.51816
// transit: +0.81965
// seting: +0.12113
}
func ExampleApproxTimes() {
// Example 15.a, p. 103.
// Venus on 1988 March 20
p := globe.Coord{
Lon: unit.NewAngle(' ', 71, 5, 0),
Lat: unit.NewAngle(' ', 42, 20, 0),
}
Th0 := unit.NewTime(' ', 11, 50, 58.1)
α := unit.NewRA(2, 46, 55.51)
δ := unit.NewAngle(' ', 18, 26, 27.3)
h0 := rise.Stdh0Stellar
tRise, tTransit, tSet, err := rise.ApproxTimes(p, h0, Th0, α, δ)
if err != nil {
fmt.Println(err)
return
}
// Units for "m" values given near top of p. 104 are day fraction.
fmt.Printf("rising: %+.5f %02s\n", tRise/86400, sexa.FmtTime(tRise))
fmt.Printf("transit: %+.5f %02s\n", tTransit/86400, sexa.FmtTime(tTransit))
fmt.Printf("seting: %+.5f %02s\n", tSet/86400, sexa.FmtTime(tSet))
// Output:
// rising: +0.51816 12ʰ26ᵐ09ˢ
// transit: +0.81965 19ʰ40ᵐ17ˢ
// seting: +0.12113 02ʰ54ᵐ26ˢ
}
func ExampleApproxTimes_computed() {
// Example 15.a, p. 103, but using meeus packages to compute values
// given in the text.
jd := julian.CalendarGregorianToJD(1988, 3, 20)
p := globe.Coord{
Lon: unit.NewAngle(' ', 71, 5, 0),
Lat: unit.NewAngle(' ', 42, 20, 0),
}
// Th0 computed rather than taken from the text.
Th0 := sidereal.Apparent0UT(jd)
fmt.Printf("Th0: %.2s\n", sexa.FmtTime(Th0))
// Venus α, δ computed rather than taken from the text.
e, err := pp.LoadPlanet(pp.Earth)
if err != nil {
fmt.Println(err)
return
}
v, err := pp.LoadPlanet(pp.Venus)
if err != nil {
fmt.Println(err)
return
}
α, δ := elliptic.Position(v, e, jd)
fmt.Printf("α: %.2s\n", sexa.FmtRA(α))
fmt.Printf("δ: %.1s\n", sexa.FmtAngle(δ))
h0 := rise.Stdh0Stellar
tRise, tTransit, tSet, err := rise.ApproxTimes(p, h0, Th0, α, δ)
if err != nil {
fmt.Println(err)
return
}
fmt.Printf("rising: %+.5f %02s\n", tRise/86400, sexa.FmtTime(tRise))
fmt.Printf("transit: %+.5f %02s\n", tTransit/86400, sexa.FmtTime(tTransit))
fmt.Printf("seting: %+.5f %02s\n", tSet/86400, sexa.FmtTime(tSet))
// Output:
// Th0: 11ʰ50ᵐ58.09ˢ
// α: 2ʰ46ᵐ55.51ˢ
// δ: 18°26′27.3″
// rising: +0.51816 12ʰ26ᵐ09ˢ
// transit: +0.81965 19ʰ40ᵐ17ˢ
// seting: +0.12113 02ʰ54ᵐ26ˢ
}
