46 lines
2.3 KiB
Go
46 lines
2.3 KiB
Go
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package basic
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import . "b612.me/astro/tools"
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// MoonBrightLimbPositionAngle 月亮明亮边缘位置角 / position angle of the Moon's bright limb.
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func MoonBrightLimbPositionAngle(jd float64) float64 {
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return MoonBrightLimbPositionAngleN(jd, -1)
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}
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// MoonBrightLimbPositionAngleN 月亮明亮边缘位置角（截断版） / truncated position angle of the Moon's bright limb.
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func MoonBrightLimbPositionAngleN(jd float64, n int) float64 {
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sunRA, sunDec := HSunApparentRaDecN(jd, n)
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moonRA, moonDec := HMoonTrueRaDecN(jd, n)
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return brightLimbPositionAngleFromRaDec(sunRA, sunDec, moonRA, moonDec)
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}
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// MoonTopocentricBrightLimbPositionAngle 月亮站心明亮边缘位置角 / topocentric position angle of the Moon's bright limb.
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func MoonTopocentricBrightLimbPositionAngle(jd, observerLon, observerLat, height float64) float64 {
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return MoonTopocentricBrightLimbPositionAngleN(jd, observerLon, observerLat, height, -1)
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}
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// MoonTopocentricBrightLimbPositionAngleN 月亮站心明亮边缘位置角（截断版） / truncated topocentric position angle of the Moon's bright limb.
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func MoonTopocentricBrightLimbPositionAngleN(jd, observerLon, observerLat, height float64, n int) float64 {
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sunRA, sunDec := sunTopocentricApparentRaDecN(jd, observerLon, observerLat, height, n)
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moonRA, moonDec := moonTopocentricApparentRaDecN(jd, observerLon, observerLat, height, n)
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return brightLimbPositionAngleFromRaDec(sunRA, sunDec, moonRA, moonDec)
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}
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func moonTopocentricApparentRaDecN(jd, observerLon, observerLat, height float64, n int) (float64, float64) {
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geocentricRA := HMoonTrueRaN(jd, n)
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geocentricDec := HMoonTrueDecN(jd, n)
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distanceAU := HMoonAwayN(jd, n) / moonPhysicalAstronomicalUnitKM
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return TopocentricRaDec(geocentricRA, geocentricDec, observerLat, observerLon, TD2UT(jd, false), distanceAU, height)
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}
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func sunTopocentricApparentRaDecN(jd, observerLon, observerLat, height float64, n int) (float64, float64) {
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geocentricRA, geocentricDec := HSunApparentRaDecN(jd, n)
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return TopocentricRaDec(geocentricRA, geocentricDec, observerLat, observerLon, TD2UT(jd, false), EarthAwayN(jd, n), height)
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}
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func brightLimbPositionAngleFromRaDec(sunRA, sunDec, bodyRA, bodyDec float64) float64 {
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y := Cos(sunDec) * Sin(sunRA-bodyRA)
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x := Sin(sunDec)*Cos(bodyDec) - Cos(sunDec)*Sin(bodyDec)*Cos(sunRA-bodyRA)
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return ArcTan2(y, x)
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}
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