func ExampleEcliptic_EqToEcl() {
// Example 13.a, p. 95.
eq := &coord.Equatorial{
unit.NewRA(7, 45, 18.946),
unit.NewAngle(' ', 28, 1, 34.26),
}
obl := coord.NewObliquity(unit.AngleFromDeg(23.4392911))
ecl := new(coord.Ecliptic).EqToEcl(eq, obl)
fmt.Printf("λ = %.5j\n", sexa.FmtAngle(ecl.Lon))
fmt.Printf("β = %+.6j\n", sexa.FmtAngle(ecl.Lat))
// Output:
// λ = 113°.21563
// β = +6°.684170
}
func ExampleEcliptic_EqToEcl() {
// Example 13.a, p. 95.
eq := &coord.Equatorial{
sexa.NewRA(7, 45, 18.946).Rad(),
sexa.NewAngle(false, 28, 1, 34.26).Rad(),
}
obl := coord.NewObliquity(23.4392911 * math.Pi / 180)
ecl := new(coord.Ecliptic).EqToEcl(eq, obl)
λStr := fmt.Sprintf("%.5j", sexa.NewFmtAngle(ecl.Lon))
βStr := fmt.Sprintf("%+.6j", sexa.NewFmtAngle(ecl.Lat))
fmt.Println("λ =", λStr)
fmt.Println("β =", βStr)
// Output:
// λ = 113°.21563
// β = +6°.684170
}
func ExampleEcliptic_EqToEcl() {
// Example 13.a, p. 95.
eq := &coord.Equatorial{
base.NewRA(7, 45, 18.946).Rad(),
base.NewAngle(false, 28, 1, 34.26).Rad(),
}
obl := coord.NewObliquity(23.4392911 * math.Pi / 180)
ecl := new(coord.Ecliptic).EqToEcl(eq, obl)
λStr := base.DecSymAdd(fmt.Sprintf("%.5f", ecl.Lon*180/math.Pi), '°')
βStr := base.DecSymAdd(fmt.Sprintf("%+.6f", ecl.Lat*180/math.Pi), '°')
fmt.Println("λ =", λStr)
fmt.Println("β =", βStr)
// Output:
// λ = 113°.21563
// β = +6°.684170
}
func TestEquatorial_EclToEq(t *testing.T) {
// repeat example above
eq0 := &coord.Equatorial{
sexa.NewRA(7, 45, 18.946).Rad(),
sexa.NewAngle(false, 28, 1, 34.26).Rad(),
}
obl := coord.NewObliquity(23.4392911 * math.Pi / 180)
ecl := new(coord.Ecliptic).EqToEcl(eq0, obl)
// now reverse transform
eq := new(coord.Equatorial).EclToEq(ecl, obl)
if math.Abs((eq.RA-eq0.RA)/eq.RA) > 1e-15 {
t.Fatal("RA:", eq0.RA, eq.RA)
}
if math.Abs((eq.Dec-eq0.Dec)/eq.Dec) > 1e-15 {
t.Fatal("Dec:", eq0.Dec, eq.Dec)
}
}
// Test with proper motion of Regulus, with equatorial motions given
// in Example 21.a, p. 132, and ecliptic motions given in table 21.A,
// p. 138.
func TestEqProperMotionToEcl(t *testing.T) {
ε := coord.NewObliquity(nutation.MeanObliquity(base.J2000))
mλ, mβ := eqProperMotionToEcl(
// eq motions from p. 132.
unit.NewHourAngle('-', 0, 0, 0.0169),
unit.NewAngle(' ', 0, 0, 0.006),
2000.0,
// eq coordinates from p. 132.
new(coord.Ecliptic).EqToEcl(&coord.Equatorial{
RA: unit.NewRA(10, 8, 22.3),
Dec: unit.NewAngle(' ', 11, 58, 2),
}, ε))
d := math.Abs((mλ - unit.AngleFromSec(-.2348)).Rad() / mλ.Rad())
if d*169 > 1 { // 169 = significant digits of given lon
t.Fatal("mλ")
}
d = math.Abs((mβ - unit.AngleFromSec(-.0813)).Rad() / mβ.Rad())
if d*6 > 1 { // 6 = significant digit of given lat
t.Fatal("mβ")
}
}
// Test with proper motion of Regulus, with equatorial motions given
// in Example 21.a, p. 132, and ecliptic motions given in table 21.A,
// p. 138.
func TestEqProperMotionToEcl(t *testing.T) {
ε := coord.NewObliquity(nutation.MeanObliquity(base.J2000))
mλ, mβ := eqProperMotionToEcl(
// eq motions from p. 132.
sexa.NewHourAngle(true, 0, 0, 0.0169).Rad(),
sexa.NewAngle(false, 0, 0, 0.006).Rad(),
2000.0,
// eq coordinates from p. 132.
new(coord.Ecliptic).EqToEcl(&coord.Equatorial{
RA: sexa.NewRA(10, 8, 22.3).Rad(),
Dec: sexa.NewAngle(false, 11, 58, 2).Rad(),
}, ε))
d := math.Abs((mλ - sexa.NewAngle(true, 0, 0, .2348).Rad()) / mλ)
if d*169 > 1 { // 169 = significant digits of given lon
t.Fatal("mλ")
}
d = math.Abs((mβ - sexa.NewAngle(true, 0, 0, 0.0813).Rad()) / mβ)
if d*6 > 1 { // 6 = significant digit of given lat
t.Fatal("mβ")
}
}
