b612
044f2f4381
- 新增半解析、旧模型、自定义与多源堆叠星历实例，提供 Context、Instance、SPK 读取及状态与视位置计算 - 统一太阳、月球和行星实例接口，扩展黄经穿越、留、相位、最近角距、偕日可见、任意高度升落、轨道节点及凌日等天象查询 - 完善日月食、月掩与凌日的月缘剖面、有限盘面接触、站心修正、局地可见性、全球路径和地图输出 - 新增 SVG、GeoJSON、KML 天象输出及凌日、月掩和月缘地形相关缓存与几何求解 - 新增恒星星表导入与查询，支持 CSV、Hipparcos、BSC5、Stellarium 等格式及名称、交叉标识、锥面检索和星等过滤 - 补充 IAU 2006、地球定向、折射消光、大气观测、轨道传播及半解析行星/月球数据支持 - 将默认未来民用时标切换为 TimeScaleLeapHour，更新 2027–2400 农历速查表、中文日期解析和时区边界处理 - 增加事件基线、跨模型回归、几何边界、月缘地形和输出契约测试，完善中英文手册、示例资源、NOTICE 与忽略规则
140 lines
5.1 KiB
Go
140 lines
5.1 KiB
Go
package basic
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import (
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"math"
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"b612.me/astro/planet"
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. "b612.me/astro/tools"
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)
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// SaturnRingParameters 土星环参数 / Saturn ring parameters.
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func SaturnRingParameters(jde float64) (earthLatitude, sunLatitude, positionAngle, deltaU, majorAxis, minorAxis float64) {
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return SaturnRingParametersN(jde, -1)
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}
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// SaturnRingParametersN 土星环参数（n 变体） / n-parameterised Saturn ring parameters.
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func SaturnRingParametersN(jde float64, n int) (earthLatitude, sunLatitude, positionAngle, deltaU, majorAxis, minorAxis float64) {
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inclination, node := saturnRingPlane(jde)
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earthLon, earthLat := SaturnApparentLoBoN(jde, n)
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sunLon, sunLat := saturnRingSunLoBo(jde, n, node)
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earthLatitude = saturnRingLatitude(inclination, node, earthLon, earthLat)
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sunLatitude = saturnRingLatitude(inclination, node, sunLon, sunLat)
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positionAngle = saturnRingPositionAngle(jde, inclination, node, earthLon, earthLat)
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earthU := saturnRingLongitude(inclination, node, earthLon, earthLat)
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sunU := saturnRingLongitude(inclination, node, sunLon, sunLat)
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deltaU = saturnRingLongitudeDelta(earthU, sunU)
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earthDistance := EarthSaturnAwayN(jde, n)
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majorAxis = 375.35 / earthDistance
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minorAxis = majorAxis * math.Abs(Sin(earthLatitude))
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return
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}
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// SaturnRingB 土星环张角 B / Saturn ring opening angle B.
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func SaturnRingB(jde float64) float64 {
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return SaturnRingBN(jde, -1)
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}
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// SaturnRingBN 土星环张角 B（n 变体） / n-parameterised Saturn ring opening angle B.
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func SaturnRingBN(jde float64, n int) float64 {
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earthLatitude, _, _, _, _, _ := SaturnRingParametersN(jde, n)
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return earthLatitude
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}
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// SaturnRingSunB 土星环太阳侧张角 B' / Sun-side Saturn ring opening angle B'.
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func SaturnRingSunB(jde float64) float64 {
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return SaturnRingSunBN(jde, -1)
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}
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// SaturnRingSunBN 土星环太阳侧张角 B'（n 变体） / n-parameterised Sun-side Saturn ring opening angle B'.
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func SaturnRingSunBN(jde float64, n int) float64 {
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_, sunLatitude, _, _, _, _ := SaturnRingParametersN(jde, n)
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return sunLatitude
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}
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// SaturnRingPositionAngle 土星环北半短轴位置角 / position angle of Saturn ring northern semiminor axis.
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func SaturnRingPositionAngle(jde float64) float64 {
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return SaturnRingPositionAngleN(jde, -1)
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}
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// SaturnRingPositionAngleN 土星环北半短轴位置角（n 变体） / n-parameterised position angle of Saturn ring northern semiminor axis.
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func SaturnRingPositionAngleN(jde float64, n int) float64 {
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_, _, positionAngle, _, _, _ := SaturnRingParametersN(jde, n)
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return positionAngle
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}
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// SaturnRingDeltaU 太阳和地球在环面内的土星心黄经差 / difference of Saturnicentric ring longitudes.
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func SaturnRingDeltaU(jde float64) float64 {
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return SaturnRingDeltaUN(jde, -1)
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}
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// SaturnRingDeltaUN 太阳和地球在环面内的土星心黄经差（n 变体） / n-parameterised Saturnicentric ring longitude difference.
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func SaturnRingDeltaUN(jde float64, n int) float64 {
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_, _, _, deltaU, _, _ := SaturnRingParametersN(jde, n)
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return deltaU
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}
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// SaturnRingAxis 土星环外缘长短轴，单位角秒 / outer ring axes in arcseconds.
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func SaturnRingAxis(jde float64) (majorAxis, minorAxis float64) {
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return SaturnRingAxisN(jde, -1)
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}
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// SaturnRingAxisN 土星环外缘长短轴（n 变体），单位角秒 / n-parameterised outer ring axes in arcseconds.
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func SaturnRingAxisN(jde float64, n int) (majorAxis, minorAxis float64) {
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_, _, _, _, majorAxis, minorAxis = SaturnRingParametersN(jde, n)
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return
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}
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func saturnRingPlane(jd float64) (inclination, node float64) {
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t := (jd - 2451545.0) / 36525.0
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inclination = 28.075216 - 0.012998*t + 0.000004*t*t
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node = 169.508470 + 1.394681*t + 0.000412*t*t
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return
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}
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func saturnRingSunLoBo(jde float64, n int, node float64) (lon, lat float64) {
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lon = planet.WherePlanetN(5, 0, jde, n)
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lat = planet.WherePlanetN(5, 1, jde, n)
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distance := planet.WherePlanetN(5, 2, jde, n)
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lat -= 0.000764 * Cos(lon-node) / distance
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lon -= 0.01759 / distance
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return lon, lat
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}
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func saturnRingLatitude(inclination, node, lon, lat float64) float64 {
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return ArcSin(Sin(inclination)*Cos(lat)*Sin(lon-node) - Cos(inclination)*Sin(lat))
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}
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func saturnRingLongitude(inclination, node, lon, lat float64) float64 {
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y := Sin(inclination)*Sin(lat) + Cos(inclination)*Cos(lat)*Sin(lon-node)
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x := Cos(lat) * Cos(lon-node)
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return ArcTan2(y, x)
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}
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func saturnRingLongitudeDelta(a, b float64) float64 {
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delta := math.Abs(Limit360(a - b))
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if delta > 180 {
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return 360 - delta
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}
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return delta
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}
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func saturnRingPositionAngle(jde, inclination, node, lon, lat float64) float64 {
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poleLon := node - 90 + Nutation2000Bi(jde)
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poleLat := 90 - inclination
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eps := TrueObliquity(jde)
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poleRa, poleDec := saturnRingEclipticToEquatorial(poleLon, poleLat, eps)
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saturnRa, saturnDec := saturnRingEclipticToEquatorial(lon, lat, eps)
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y := Cos(poleDec) * Sin(poleRa-saturnRa)
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x := Sin(poleDec)*Cos(saturnDec) - Cos(poleDec)*Sin(saturnDec)*Cos(poleRa-saturnRa)
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return ArcTan2(y, x)
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}
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func saturnRingEclipticToEquatorial(lon, lat, eps float64) (ra, dec float64) {
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ra = ArcTan2(Sin(lon)*Cos(eps)-Tan(lat)*Sin(eps), Cos(lon))
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dec = ArcSin(Sin(lat)*Cos(eps) + Cos(lat)*Sin(eps)*Sin(lon))
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return
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}
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