astro/basic/moon_observation.go

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package basic
import (
"math"
. "b612.me/astro/tools"
)
/*
* 月球方位角
*/
func MoonAzimuth(jd, lon, lat, tz float64) float64 {
//tmp := (tz*15 - lon) * 4 / 60
calcjd := TD2UT(jd-tz/24, true)
ra := MoonTrueRa(calcjd)
dec := MoonTrueDec(calcjd)
away := MoonAway(calcjd) / 149597870.7
ndec := TopocentricDec(ra, dec, lat, lon, jd-tz/24, away, 0)
nra := TopocentricRa(ra, dec, lat, lon, jd-tz/24, away, 0)
calcjd = jd - tz/24
st := Limit360(ApparentSiderealTime(calcjd)*15 + lon)
hourAngle := Limit360(st - nra)
tmp2 := Sin(hourAngle) / (Cos(hourAngle)*Sin(lat) - Tan(ndec)*Cos(lat))
azimuth := ArcTan(tmp2)
if azimuth < 0 {
if hourAngle/15 < 12 {
return azimuth + 360
} else {
return azimuth + 180
}
} else {
if hourAngle/15 < 12 {
return azimuth + 180
} else {
return azimuth
}
}
}
func MoonHeight(jd, lon, lat, tz float64) float64 {
// tmp := (tz*15 - lon) * 4 / 60
//truejd=jd-tmp/24;
calcjd := TD2UT(jd-tz/24, true)
ra := MoonTrueRa(calcjd)
dec := MoonTrueDec(calcjd)
away := MoonAway(calcjd) / 149597870.7
ndec := TopocentricDec(ra, dec, lat, lon, jd-tz/24, away, 0)
nra := TopocentricRa(ra, dec, lat, lon, jd-tz/24, away, 0)
calcjd = jd - tz/24
st := Limit360(ApparentSiderealTime(calcjd)*15 + lon)
hourAngle := Limit360(st - nra)
tmp2 := Sin(lat)*Sin(ndec) + Cos(ndec)*Cos(lat)*Cos(hourAngle)
return ArcSin(tmp2)
}
func HMoonAzimuth(jd, lon, lat, tz float64) float64 {
return HMoonAzimuthN(jd, lon, lat, tz, -1)
}
func HMoonAzimuthN(jd, lon, lat, tz float64, n int) float64 {
calcjd := TD2UT(jd-tz/24, true)
ra := HMoonTrueRaN(calcjd, n)
dec := HMoonTrueDecN(calcjd, n)
away := HMoonAwayN(calcjd, n) / 149597870.7
ndec := TopocentricDec(ra, dec, lat, lon, jd-tz/24, away, 0)
nra := TopocentricRa(ra, dec, lat, lon, jd-tz/24, away, 0)
calcjd = jd - tz/24
st := Limit360(ApparentSiderealTime(calcjd)*15 + lon)
hourAngle := Limit360(st - nra)
tmp2 := Sin(hourAngle) / (Cos(hourAngle)*Sin(lat) - Tan(ndec)*Cos(lat))
azimuth := ArcTan(tmp2)
if azimuth < 0 {
if hourAngle/15 < 12 {
return azimuth + 360
} else {
return azimuth + 180
}
} else {
if hourAngle/15 < 12 {
return azimuth + 180
} else {
return azimuth
}
}
}
func HMoonHeight(jd, lon, lat, tz float64) float64 {
return HMoonHeightN(jd, lon, lat, tz, -1)
}
func HMoonHeightN(jd, lon, lat, tz float64, n int) float64 {
calcjd := TD2UT(jd-tz/24, true)
ra, dec := HMoonTrueRaDecN(calcjd, n)
away := HMoonAwayN(calcjd, n) / 149597870.7
nra, ndec := TopocentricRaDec(ra, dec, lat, lon, calcjd, away, 0)
calcjd = jd - tz/24
st := Limit360(ApparentSiderealTime(calcjd)*15 + lon)
hourAngle := Limit360(st - nra)
tmp2 := Sin(lat)*Sin(ndec) + Cos(ndec)*Cos(lat)*Cos(hourAngle)
return ArcSin(tmp2)
}
// 废弃
func GetMoonTZTime(jd, lon, lat, tz float64) float64 { //实际中天时间{
jd = math.Floor(jd) + 0.5
ttm := MoonTimeAngle(jd, lon, lat, tz)
if ttm > 0 && ttm < 180 {
jd += 0.5
}
estimateJD := jd
for {
prevJD := estimateJD
stDegree := MoonTimeAngle(prevJD, lon, lat, tz) - 359.599
stDegreep := (MoonTimeAngle(prevJD+0.000005, lon, lat, tz) - MoonTimeAngle(prevJD-0.000005, lon, lat, tz)) / 0.00001
estimateJD = prevJD - stDegree/stDegreep
if math.Abs(estimateJD-prevJD) <= 0.00001 {
break
}
}
return estimateJD
}
func MoonCulminationTime(jde, lon, lat, timezone float64) float64 {
//jde 世界时,非力学时,当地时区 0时无需转换力学时
//ra,dec 瞬时天球座标非J2000等时间天球坐标
jde = math.Floor(jde) + 0.5
estimateJD := jde + Limit360(360-MoonTimeAngle(jde, lon, lat, timezone))/15.0/24.0/0.9
limitHA := func(jde, lon, timezone float64) float64 {
ha := MoonTimeAngle(jde, lon, lat, timezone)
if ha < 180 {
ha += 360
}
return ha
}
for {
prevJD := estimateJD
stDegree := limitHA(prevJD, lon, timezone) - 360
stDegreep := (limitHA(prevJD+0.000005, lon, timezone) - limitHA(prevJD-0.000005, lon, timezone)) / 0.00001
estimateJD = prevJD - stDegree/stDegreep
if math.Abs(estimateJD-prevJD) <= 0.00001 {
break
}
}
return estimateJD
}
func MoonTimeAngle(jd, lon, lat, tz float64) float64 {
startime := Limit360(ApparentSiderealTime(jd-tz/24)*15 + lon)
timeangle := startime - HMoonApparentRa(jd, lon, lat, tz)
if timeangle < 0 {
timeangle += 360
}
return timeangle
}
func GetMoonRiseTime(julianDay, longitude, latitude, timeZone, zenithShift, height float64) (float64, error) {
originalTimeZone := timeZone
timeZone = longitude / 15
var timeToMeridian float64
julianDayZero := math.Floor(julianDay) + 0.5
//julianDay = math.Floor(julianDay) + 0.5 - originalTimeZone/24 + timeZone/24 // 求0时JDE
//fix:这里时间分界线应当以传入的时区为准不应当使用当地时区否则在0时的判断会出错
julianDay = math.Floor(julianDay) + 0.5
estimatedTime := julianDay
moonHeight := MoonHeight(julianDay, longitude, latitude, originalTimeZone) // 求此时月亮高度
moonAngle := StandardAltitudeMoon(zenithShift, height, latitude)
moonAngleTime := MoonTimeAngle(julianDay, longitude, latitude, originalTimeZone)
if moonHeight-moonAngle > 0 { // 月亮在地平线上或在落下与下中天之间
if moonAngleTime > 180 {
timeToMeridian = (180 + 360 - moonAngleTime) / 15
} else {
timeToMeridian = (180 - moonAngleTime) / 15
}
estimatedTime += (timeToMeridian/24 + (timeToMeridian/24*12.0)/15.0/24.0)
}
if moonHeight-moonAngle < 0 && moonAngleTime > 180 {
timeToMeridian = (180 - moonAngleTime) / 15
estimatedTime += (timeToMeridian/24 + (timeToMeridian/24*12.0)/15.0/24.0)
} else if moonHeight-moonAngle < 0 && moonAngleTime < 180 {
timeToMeridian = (180 - moonAngleTime) / 15
estimatedTime += (timeToMeridian/24 + (timeToMeridian/24*12.0)/15.0/24.0)
}
currentAngle := MoonTimeAngle(estimatedTime, longitude, latitude, timeZone)
if math.Abs(currentAngle-180) > 0.5 {
estimatedTime += (180 - currentAngle) * 4.0 / 60.0 / 24.0
}
currentHeight := HMoonHeight(estimatedTime, longitude, latitude, timeZone)
if !(currentHeight < -10 && math.Abs(latitude) < 60) {
if currentHeight > moonAngle {
return 0, ErrNeverSet
}
checkTime := estimatedTime + 12.0/24.0 + 6.0/15.0/24.0
checkAngle := MoonTimeAngle(checkTime, longitude, latitude, timeZone)
if checkAngle < 90 {
checkAngle += 360
}
checkTime += (360 - checkAngle) * 4.0 / 60.0 / 24.0
if HMoonHeight(checkTime, longitude, latitude, timeZone) < moonAngle {
return 0, ErrNeverRise
}
}
moonDeclination := MoonApparentDec(estimatedTime, longitude, latitude, timeZone)
tmp := (Sin(moonAngle) - Sin(moonDeclination)*Sin(latitude)) / (Cos(moonDeclination) * Cos(latitude))
if math.Abs(tmp) <= 1 && latitude < 85 {
hourAngle := (180 - ArcCos(tmp)) / 15
estimatedTime += hourAngle/24.00 + hourAngle/33.00/15.00
} else {
i := 0
for MoonHeight(estimatedTime, longitude, latitude, timeZone) < moonAngle {
i++
estimatedTime += 15.0 / 60.0 / 24.0
if i > 48 {
break
}
}
}
// 使用牛顿迭代法求精确解
estimatedTime = moonRiseSetNewtonRaphsonIteration(estimatedTime, longitude, latitude, timeZone, moonAngle, HMoonHeight, 0.00002)
estimatedTime = estimatedTime - timeZone/24 + originalTimeZone/24
if estimatedTime > julianDayZero+1 || estimatedTime < julianDayZero {
return 0, ErrNotOnThisDate
}
return estimatedTime, nil
}
func GetMoonSetTime(julianDay, longitude, latitude, timeZone, zenithShift, height float64) (float64, error) {
originalTimeZone := timeZone
timeZone = longitude / 15
var timeToMeridian float64
julianDayZero := math.Floor(julianDay) + 0.5
//julianDay = math.Floor(julianDay) + 0.5 - originalTimeZone/24 + timeZone/24 // 求0时JDE
//fix:这里时间分界线应当以传入的时区为准不应当使用当地时区否则在0时的判断会出错
julianDay = math.Floor(julianDay) + 0.5
estimatedTime := julianDay
moonHeight := MoonHeight(julianDay, longitude, latitude, originalTimeZone) // 求此时月亮高度
moonAngle := StandardAltitudeMoon(zenithShift, height, latitude)
moonAngleTime := MoonTimeAngle(julianDay, longitude, latitude, originalTimeZone)
if moonHeight-moonAngle < 0 {
timeToMeridian = (360 - moonAngleTime) / 15
estimatedTime += (timeToMeridian/24 + (timeToMeridian/24.0*12.0)/15.0/24.0)
}
// 月亮在地平线上或在落下与下中天之间
if moonHeight-moonAngle > 0 && moonAngleTime < 180 {
timeToMeridian = (-moonAngleTime) / 15
estimatedTime += (timeToMeridian/24.0 + (timeToMeridian/24.0*12.0)/15.0/24.0)
} else if moonHeight-moonAngle > 0 {
timeToMeridian = (360 - moonAngleTime) / 15
estimatedTime += (timeToMeridian/24.0 + (timeToMeridian/24.0*12.0)/15.0/24.0)
}
currentAngle := MoonTimeAngle(estimatedTime, longitude, latitude, timeZone)
if currentAngle < 180 {
currentAngle += 360
}
if math.Abs(currentAngle-360) > 0.5 {
estimatedTime += (360 - currentAngle) * 4.0 / 60.0 / 24.0
}
// estimatedTime = 月球中天时间
currentHeight := HMoonHeight(estimatedTime, longitude, latitude, timeZone)
if !(currentHeight > 10 && math.Abs(latitude) < 60) {
if currentHeight < moonAngle {
return 0, ErrNeverRise
}
checkTime := estimatedTime + 12.0/24.0 + 6.0/15.0/24.0
angleSubtraction := 180 - MoonTimeAngle(checkTime, longitude, latitude, timeZone)
checkTime += angleSubtraction * 4.0 / 60.0 / 24.0
if HMoonHeight(checkTime, longitude, latitude, timeZone) > moonAngle {
return 0, ErrNeverSet
}
}
moonDeclination := MoonApparentDec(estimatedTime, longitude, latitude, timeZone)
tmp := (Sin(moonAngle) - Sin(moonDeclination)*Sin(latitude)) / (Cos(moonDeclination) * Cos(latitude))
if math.Abs(tmp) <= 1 && latitude < 85 {
hourAngle := (ArcCos(tmp)) / 15.0
estimatedTime += hourAngle/24 + hourAngle/33.0/15.0
} else {
i := 0
for MoonHeight(estimatedTime, longitude, latitude, timeZone) > moonAngle {
i++
estimatedTime += 15.0 / 60.0 / 24.0
if i > 48 {
break
}
}
}
// 使用牛顿迭代法求精确解
estimatedTime = moonRiseSetNewtonRaphsonIteration(estimatedTime, longitude, latitude, timeZone, moonAngle, HMoonHeight, 0.00002)
estimatedTime = estimatedTime - timeZone/24 + originalTimeZone/24
if estimatedTime > julianDayZero+1 || estimatedTime < julianDayZero {
return 0, ErrNotOnThisDate
}
return estimatedTime, nil
}
// heightFunction 高度函数类型定义,用于牛顿迭代法
type heightFunction func(time, longitude, latitude, timeZone float64) float64
// moonRiseSetNewtonRaphsonIteration 牛顿-拉夫逊迭代法求解天体高度方程
func moonRiseSetNewtonRaphsonIteration(initialTime, longitude, latitude, timeZone, targetAngle float64,
heightFunc heightFunction, tolerance float64) float64 {
const derivativeStep = 0.000005
currentTime := initialTime
for {
previousTime := currentTime
// 计算函数值f(t) = height(t) - targetAngle
functionValue := heightFunc(previousTime, longitude, latitude, timeZone) - targetAngle
// 计算导数f'(t) ≈ (f(t+h) - f(t-h)) / (2h)
derivative := (heightFunc(previousTime+derivativeStep, longitude, latitude, timeZone) -
heightFunc(previousTime-derivativeStep, longitude, latitude, timeZone)) / (2 * derivativeStep)
// 牛顿-拉夫逊公式t_new = t_old - f(t) / f'(t)
currentTime = previousTime - functionValue/derivative
// 检查收敛
if math.Abs(currentTime-previousTime) <= tolerance {
break
}
}
return currentTime
}