b612
2bf8478639
- 新增日月食中心带、偏食带、阴影足迹、等时线、食分线及升落边界计算，支持极区与混合食拓扑 - 新增日食单时刻阴影求解器、站心状态查询、批量采样和 ΔT 覆盖接口 - 重构恒星与行星月掩路径，补充有限盘面接触、站心修正、掩带宽度、极区投影及升落边界 - 扩展 SVG 与 GeoJSON 输出，支持详细面板、全球/极区/地球投影、边界闭合、时间标记和拓扑签名 - 扩展日月食候选搜索、局地搜索、沙罗序列预计算与范围外推，补充系列锚点和成员一致性校验 - 补齐古历纪年、儒略历独有闰日、多公历候选、历法改革跨日及精确日期运算接口 - 优化 ΔT、章动、恒星时、月球地平线、事件根搜索和本地星历缓存，降低重复计算开销并提升边界稳定
500 lines
22 KiB
Go
500 lines
22 KiB
Go
package eclipse
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import (
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"math"
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"time"
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"b612.me/astro/basic"
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)
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const localLunarEclipseSearchLimit = 6000
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type localLunarEclipseQueryMode int
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const (
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localLunarEclipseQueryVisible localLunarEclipseQueryMode = iota
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localLunarEclipseQueryGeometric
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)
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// LocalLunarEclipseInfo 站点月食信息, local lunar eclipse information.
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//
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// 所有时刻字段都保持用户输入的时区。
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// 不存在的阶段使用零值 time.Time。
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type LocalLunarEclipseInfo struct {
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// Type 月食类型, eclipse type.
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Type LunarEclipseType
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// HasSaros 存在沙罗序列信息（可能是锚点外推结果）, has Saros series metadata (possibly extrapolated).
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HasSaros bool
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// Saros 是沙罗序列信息，包括系列号、系列内序号和总成员数。
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// Saros is Saros series metadata with the series number, member index, and total member count.
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Saros SarosInfo
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// Longitude 观测点经度，东正西负, observer longitude, east positive.
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Longitude float64
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// Latitude 观测点纬度，北正南负, observer latitude, north positive.
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Latitude float64
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// Height 观测点海拔高度，单位米, observer height in meters.
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Height float64
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// PenumbralMagnitude 半影食分, penumbral magnitude.
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PenumbralMagnitude float64
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// UmbralMagnitude 本影食分；纯半影月食时可为负值, umbral magnitude; can be negative for purely penumbral eclipses.
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UmbralMagnitude float64
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// PenumbralStart 半影始, penumbral eclipse begins.
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PenumbralStart time.Time
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// PartialStart 初亏, partial eclipse begins.
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PartialStart time.Time
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// TotalStart 食既, total eclipse begins.
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TotalStart time.Time
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// Maximum 食甚, greatest eclipse.
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Maximum time.Time
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// TotalEnd 生光, total eclipse ends.
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TotalEnd time.Time
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// PartialEnd 复圆, partial eclipse ends.
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PartialEnd time.Time
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// PenumbralEnd 半影终, penumbral eclipse ends.
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PenumbralEnd time.Time
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// MoonAltitude 食甚时月亮高度角，单位度, Moon altitude at maximum in degrees.
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MoonAltitude float64
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// MoonAzimuth 食甚时月亮方位角，单位度, Moon azimuth at maximum in degrees.
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MoonAzimuth float64
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// VisibleAtMaximum 食甚时月亮中心在本地几何地平线上方, Moon center above the local geometric horizon at maximum.
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VisibleAtMaximum bool
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// HasPenumbral 有半影阶段, has penumbral phase.
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HasPenumbral bool
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// HasPartial 有偏食阶段, has partial phase.
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HasPartial bool
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// HasTotal 有全食阶段, has total phase.
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HasTotal bool
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}
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// LocalLunarEclipseOnDate 当地可见月食查询 / local visible lunar eclipse query.
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// Determine whether a visible local lunar eclipse occurs on the local date, using Danjon by default.
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func LocalLunarEclipseOnDate(date time.Time, lon, lat, height float64) (LocalLunarEclipseInfo, bool) {
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return LocalLunarEclipseOnDateDanjon(date, lon, lat, height)
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}
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// LocalLunarEclipseOnDateDanjon 当地可见月食查询（Danjon） / local visible lunar eclipse query with Danjon model.
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// Determine whether a visible local lunar eclipse occurs on the local date with the Danjon model.
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func LocalLunarEclipseOnDateDanjon(date time.Time, lon, lat, height float64) (LocalLunarEclipseInfo, bool) {
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return localLunarEclipseOnDate(date, lon, lat, height, basic.LunarEclipseDanjon, localLunarEclipseQueryVisible)
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}
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// LocalLunarEclipseOnDateChauvenet 当地可见月食查询（Chauvenet） / local visible lunar eclipse query with Chauvenet model.
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// Determine whether a visible local lunar eclipse occurs on the local date with the Chauvenet model.
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func LocalLunarEclipseOnDateChauvenet(date time.Time, lon, lat, height float64) (LocalLunarEclipseInfo, bool) {
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return localLunarEclipseOnDate(date, lon, lat, height, basic.LunarEclipseChauvenet, localLunarEclipseQueryVisible)
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}
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// GeometricLocalLunarEclipseOnDate 当地几何月食查询 / local geometric lunar eclipse query.
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// Determine whether a geometric local lunar eclipse occurs on the local date, using Danjon by default.
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func GeometricLocalLunarEclipseOnDate(date time.Time, lon, lat, height float64) (LocalLunarEclipseInfo, bool) {
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return GeometricLocalLunarEclipseOnDateDanjon(date, lon, lat, height)
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}
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// GeometricLocalLunarEclipseOnDateDanjon 当地几何月食查询（Danjon） / local geometric lunar eclipse query with Danjon model.
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// Determine whether a geometric local lunar eclipse occurs on the local date with the Danjon model.
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func GeometricLocalLunarEclipseOnDateDanjon(date time.Time, lon, lat, height float64) (LocalLunarEclipseInfo, bool) {
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return localLunarEclipseOnDate(date, lon, lat, height, basic.LunarEclipseDanjon, localLunarEclipseQueryGeometric)
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}
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// GeometricLocalLunarEclipseOnDateChauvenet 当地几何月食查询（Chauvenet） / local geometric lunar eclipse query with Chauvenet model.
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// Determine whether a geometric local lunar eclipse occurs on the local date with the Chauvenet model.
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func GeometricLocalLunarEclipseOnDateChauvenet(date time.Time, lon, lat, height float64) (LocalLunarEclipseInfo, bool) {
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return localLunarEclipseOnDate(date, lon, lat, height, basic.LunarEclipseChauvenet, localLunarEclipseQueryGeometric)
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}
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func localLunarEclipseOnDate(
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date time.Time,
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lon, lat, height float64,
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calculator lunarEclipseCalculator,
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mode localLunarEclipseQueryMode,
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) (LocalLunarEclipseInfo, bool) {
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location := date.Location()
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dayStart, dayMid, dayEnd := lunarEclipseLocalDayBounds(date)
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phaseDiff := moonSunLoDiff(dayMid)
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if phaseDiff < lunarEclipseDayPhaseMin || phaseDiff > lunarEclipseDayPhaseMax {
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return LocalLunarEclipseInfo{}, false
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}
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candidateTT := basic.CalcMoonSHByJDE(timeToTTJDE(dayMid), 1)
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if !isPotentialLunarEclipse(candidateTT) {
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return LocalLunarEclipseInfo{}, false
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}
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result := calculator(candidateTT)
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if result.Type == basic.LunarEclipseNone {
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return LocalLunarEclipseInfo{}, false
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}
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info := localLunarEclipseInfoFromBasic(result, lon, lat, height, location)
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if !localLunarEclipseOverlapsDate(info, dayStart, dayEnd) {
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return LocalLunarEclipseInfo{}, false
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}
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if mode == localLunarEclipseQueryVisible && !localLunarEclipseVisibleOnDate(info, dayStart, dayEnd) {
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return LocalLunarEclipseInfo{}, false
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}
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return info, true
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}
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// LastLocalLunarEclipse 上次可见月食 / previous visible local lunar eclipse.
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// Previous visible local lunar eclipse, using Danjon by default.
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func LastLocalLunarEclipse(date time.Time, lon, lat, height float64) LocalLunarEclipseInfo {
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return LastLocalLunarEclipseDanjon(date, lon, lat, height)
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}
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// LastLocalTotalLunarEclipse 上次可见月全食 / previous visible local total lunar eclipse.
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// Previous visible local total lunar eclipse, using Danjon by default.
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func LastLocalTotalLunarEclipse(date time.Time, lon, lat, height float64) (LocalLunarEclipseInfo, bool) {
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return searchLocalTotalLunarEclipse(date, lon, lat, height, -1, true, basic.LunarEclipseDanjon, localLunarEclipseQueryVisible)
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}
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// LastLocalLunarEclipseDanjon 上次可见月食（Danjon） / previous visible local lunar eclipse with Danjon model.
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// Previous visible local lunar eclipse with the Danjon model.
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func LastLocalLunarEclipseDanjon(date time.Time, lon, lat, height float64) LocalLunarEclipseInfo {
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info, _ := searchLocalLunarEclipse(date, lon, lat, height, -1, true, basic.LunarEclipseDanjon, localLunarEclipseQueryVisible)
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return info
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}
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// LastLocalLunarEclipseChauvenet 上次可见月食（Chauvenet） / previous visible local lunar eclipse with Chauvenet model.
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// Previous visible local lunar eclipse with the Chauvenet model.
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func LastLocalLunarEclipseChauvenet(date time.Time, lon, lat, height float64) LocalLunarEclipseInfo {
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info, _ := searchLocalLunarEclipse(date, lon, lat, height, -1, true, basic.LunarEclipseChauvenet, localLunarEclipseQueryVisible)
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return info
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}
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// LastGeometricLocalLunarEclipse 上次几何月食 / previous geometric local lunar eclipse.
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// Previous geometric local lunar eclipse, using Danjon by default.
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func LastGeometricLocalLunarEclipse(date time.Time, lon, lat, height float64) LocalLunarEclipseInfo {
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return LastGeometricLocalLunarEclipseDanjon(date, lon, lat, height)
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}
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// LastGeometricLocalLunarEclipseDanjon 上次几何月食（Danjon） / previous geometric local lunar eclipse with Danjon model.
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// Previous geometric local lunar eclipse with the Danjon model.
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func LastGeometricLocalLunarEclipseDanjon(date time.Time, lon, lat, height float64) LocalLunarEclipseInfo {
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info, _ := searchLocalLunarEclipse(date, lon, lat, height, -1, true, basic.LunarEclipseDanjon, localLunarEclipseQueryGeometric)
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return info
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}
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// LastGeometricLocalLunarEclipseChauvenet 上次几何月食（Chauvenet） / previous geometric local lunar eclipse with Chauvenet model.
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// Previous geometric local lunar eclipse with the Chauvenet model.
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func LastGeometricLocalLunarEclipseChauvenet(date time.Time, lon, lat, height float64) LocalLunarEclipseInfo {
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info, _ := searchLocalLunarEclipse(date, lon, lat, height, -1, true, basic.LunarEclipseChauvenet, localLunarEclipseQueryGeometric)
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return info
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}
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// NextLocalLunarEclipse 下次可见月食 / next visible local lunar eclipse.
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// Next visible local lunar eclipse, using Danjon by default.
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func NextLocalLunarEclipse(date time.Time, lon, lat, height float64) LocalLunarEclipseInfo {
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return NextLocalLunarEclipseDanjon(date, lon, lat, height)
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}
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// NextLocalTotalLunarEclipse 下次可见月全食 / next visible local total lunar eclipse.
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// Next visible local total lunar eclipse, using Danjon by default.
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func NextLocalTotalLunarEclipse(date time.Time, lon, lat, height float64) (LocalLunarEclipseInfo, bool) {
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return searchLocalTotalLunarEclipse(date, lon, lat, height, 1, false, basic.LunarEclipseDanjon, localLunarEclipseQueryVisible)
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}
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// NextLocalLunarEclipseDanjon 下次可见月食（Danjon） / next visible local lunar eclipse with Danjon model.
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// Next visible local lunar eclipse with the Danjon model.
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func NextLocalLunarEclipseDanjon(date time.Time, lon, lat, height float64) LocalLunarEclipseInfo {
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info, _ := searchLocalLunarEclipse(date, lon, lat, height, 1, false, basic.LunarEclipseDanjon, localLunarEclipseQueryVisible)
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return info
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}
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// NextLocalLunarEclipseChauvenet 下次可见月食（Chauvenet） / next visible local lunar eclipse with Chauvenet model.
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// Next visible local lunar eclipse with the Chauvenet model.
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func NextLocalLunarEclipseChauvenet(date time.Time, lon, lat, height float64) LocalLunarEclipseInfo {
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info, _ := searchLocalLunarEclipse(date, lon, lat, height, 1, false, basic.LunarEclipseChauvenet, localLunarEclipseQueryVisible)
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return info
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}
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// NextGeometricLocalLunarEclipse 下次几何月食 / next geometric local lunar eclipse.
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// Next geometric local lunar eclipse, using Danjon by default.
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func NextGeometricLocalLunarEclipse(date time.Time, lon, lat, height float64) LocalLunarEclipseInfo {
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return NextGeometricLocalLunarEclipseDanjon(date, lon, lat, height)
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}
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// NextGeometricLocalLunarEclipseDanjon 下次几何月食（Danjon） / next geometric local lunar eclipse with Danjon model.
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// Next geometric local lunar eclipse with the Danjon model.
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func NextGeometricLocalLunarEclipseDanjon(date time.Time, lon, lat, height float64) LocalLunarEclipseInfo {
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info, _ := searchLocalLunarEclipse(date, lon, lat, height, 1, false, basic.LunarEclipseDanjon, localLunarEclipseQueryGeometric)
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return info
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}
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// NextGeometricLocalLunarEclipseChauvenet 下次几何月食（Chauvenet） / next geometric local lunar eclipse with Chauvenet model.
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// Next geometric local lunar eclipse with the Chauvenet model.
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func NextGeometricLocalLunarEclipseChauvenet(date time.Time, lon, lat, height float64) LocalLunarEclipseInfo {
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info, _ := searchLocalLunarEclipse(date, lon, lat, height, 1, false, basic.LunarEclipseChauvenet, localLunarEclipseQueryGeometric)
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return info
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}
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// ClosestLocalLunarEclipse 最近一次可见月食 / closest visible local lunar eclipse.
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// Closest visible local lunar eclipse, using Danjon by default.
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func ClosestLocalLunarEclipse(date time.Time, lon, lat, height float64) LocalLunarEclipseInfo {
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return ClosestLocalLunarEclipseDanjon(date, lon, lat, height)
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}
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// ClosestLocalTotalLunarEclipse 最近一次可见月全食 / closest visible local total lunar eclipse.
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// Closest visible local total lunar eclipse, using Danjon by default.
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func ClosestLocalTotalLunarEclipse(date time.Time, lon, lat, height float64) (LocalLunarEclipseInfo, bool) {
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last, hasLast := searchLocalTotalLunarEclipse(date, lon, lat, height, -1, true, basic.LunarEclipseDanjon, localLunarEclipseQueryVisible)
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next, hasNext := searchLocalTotalLunarEclipse(date, lon, lat, height, 1, false, basic.LunarEclipseDanjon, localLunarEclipseQueryVisible)
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return closestLocalLunarEclipseResult(date, last, hasLast, next, hasNext)
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}
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// ClosestLocalLunarEclipseDanjon 最近一次可见月食（Danjon） / closest visible local lunar eclipse with Danjon model.
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// Closest visible local lunar eclipse with the Danjon model.
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func ClosestLocalLunarEclipseDanjon(date time.Time, lon, lat, height float64) LocalLunarEclipseInfo {
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last, hasLast := searchLocalLunarEclipse(date, lon, lat, height, -1, true, basic.LunarEclipseDanjon, localLunarEclipseQueryVisible)
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next, hasNext := searchLocalLunarEclipse(date, lon, lat, height, 1, false, basic.LunarEclipseDanjon, localLunarEclipseQueryVisible)
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return closestLocalLunarEclipse(date, last, hasLast, next, hasNext)
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}
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// ClosestLocalLunarEclipseChauvenet 最近一次可见月食（Chauvenet） / closest visible local lunar eclipse with Chauvenet model.
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// Closest visible local lunar eclipse with the Chauvenet model.
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func ClosestLocalLunarEclipseChauvenet(date time.Time, lon, lat, height float64) LocalLunarEclipseInfo {
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last, hasLast := searchLocalLunarEclipse(date, lon, lat, height, -1, true, basic.LunarEclipseChauvenet, localLunarEclipseQueryVisible)
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next, hasNext := searchLocalLunarEclipse(date, lon, lat, height, 1, false, basic.LunarEclipseChauvenet, localLunarEclipseQueryVisible)
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return closestLocalLunarEclipse(date, last, hasLast, next, hasNext)
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}
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// ClosestGeometricLocalLunarEclipse 最近一次几何月食 / closest geometric local lunar eclipse.
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// Closest geometric local lunar eclipse, using Danjon by default.
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func ClosestGeometricLocalLunarEclipse(date time.Time, lon, lat, height float64) LocalLunarEclipseInfo {
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return ClosestGeometricLocalLunarEclipseDanjon(date, lon, lat, height)
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}
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// ClosestGeometricLocalLunarEclipseDanjon 最近一次几何月食（Danjon） / closest geometric local lunar eclipse with Danjon model.
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// Closest geometric local lunar eclipse with the Danjon model.
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func ClosestGeometricLocalLunarEclipseDanjon(date time.Time, lon, lat, height float64) LocalLunarEclipseInfo {
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last, hasLast := searchLocalLunarEclipse(date, lon, lat, height, -1, true, basic.LunarEclipseDanjon, localLunarEclipseQueryGeometric)
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next, hasNext := searchLocalLunarEclipse(date, lon, lat, height, 1, false, basic.LunarEclipseDanjon, localLunarEclipseQueryGeometric)
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return closestLocalLunarEclipse(date, last, hasLast, next, hasNext)
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}
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// ClosestGeometricLocalLunarEclipseChauvenet 最近一次几何月食（Chauvenet） / closest geometric local lunar eclipse with Chauvenet model.
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// Closest geometric local lunar eclipse with the Chauvenet model.
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func ClosestGeometricLocalLunarEclipseChauvenet(date time.Time, lon, lat, height float64) LocalLunarEclipseInfo {
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last, hasLast := searchLocalLunarEclipse(date, lon, lat, height, -1, true, basic.LunarEclipseChauvenet, localLunarEclipseQueryGeometric)
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next, hasNext := searchLocalLunarEclipse(date, lon, lat, height, 1, false, basic.LunarEclipseChauvenet, localLunarEclipseQueryGeometric)
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return closestLocalLunarEclipse(date, last, hasLast, next, hasNext)
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}
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func closestLocalLunarEclipse(
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date time.Time,
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last LocalLunarEclipseInfo,
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hasLast bool,
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next LocalLunarEclipseInfo,
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hasNext bool,
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) LocalLunarEclipseInfo {
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info, _ := closestLocalLunarEclipseResult(date, last, hasLast, next, hasNext)
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return info
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}
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func closestLocalLunarEclipseResult(
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date time.Time,
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last LocalLunarEclipseInfo,
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hasLast bool,
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next LocalLunarEclipseInfo,
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hasNext bool,
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) (LocalLunarEclipseInfo, bool) {
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switch {
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case hasLast && !hasNext:
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return last, true
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case !hasLast && hasNext:
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return next, true
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case !hasLast && !hasNext:
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return LocalLunarEclipseInfo{}, false
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}
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lastDistance := math.Abs(date.Sub(last.Maximum).Seconds())
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nextDistance := math.Abs(next.Maximum.Sub(date).Seconds())
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if lastDistance <= nextDistance {
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return last, true
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}
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return next, true
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}
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func searchLocalLunarEclipse(
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date time.Time,
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lon, lat, height float64,
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direction int,
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includeCurrent bool,
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calculator lunarEclipseCalculator,
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mode localLunarEclipseQueryMode,
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) (LocalLunarEclipseInfo, bool) {
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targetTT := timeToTTJDE(date)
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candidateTT := basic.CalcMoonSHByJDE(targetTT, 1)
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for i := 0; i < localLunarEclipseSearchLimit; i++ {
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if isPotentialLunarEclipse(candidateTT) {
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result := calculator(candidateTT)
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if result.Type != basic.LunarEclipseNone {
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info := localLunarEclipseInfoFromBasic(result, lon, lat, height, date.Location())
|
||
if (mode != localLunarEclipseQueryVisible || localLunarEclipseVisible(info)) &&
|
||
lunarEclipseMatchesDirection(result.Maximum, targetTT, direction, includeCurrent) {
|
||
return info, true
|
||
}
|
||
}
|
||
}
|
||
candidateTT = nextEclipseSearchCandidateTT(candidateTT, 1, direction, lunarEclipseSynodicMonthDays)
|
||
}
|
||
|
||
return LocalLunarEclipseInfo{}, false
|
||
}
|
||
|
||
func searchLocalTotalLunarEclipse(
|
||
date time.Time,
|
||
lon, lat, height float64,
|
||
direction int,
|
||
includeCurrent bool,
|
||
calculator lunarEclipseCalculator,
|
||
mode localLunarEclipseQueryMode,
|
||
) (LocalLunarEclipseInfo, bool) {
|
||
targetTT := timeToTTJDE(date)
|
||
candidateTT := basic.CalcMoonSHByJDE(targetTT, 1)
|
||
|
||
for i := 0; i < localLunarEclipseSearchLimit; i++ {
|
||
if isPotentialLunarEclipse(candidateTT) {
|
||
result := calculator(candidateTT)
|
||
if result.HasTotal {
|
||
info := localLunarEclipseInfoFromBasic(result, lon, lat, height, date.Location())
|
||
if (mode != localLunarEclipseQueryVisible || localTotalLunarEclipseVisible(info)) &&
|
||
lunarEclipseMatchesDirection(result.Maximum, targetTT, direction, includeCurrent) {
|
||
return info, true
|
||
}
|
||
}
|
||
}
|
||
candidateTT = nextEclipseSearchCandidateTT(candidateTT, 1, direction, lunarEclipseSynodicMonthDays)
|
||
}
|
||
|
||
return LocalLunarEclipseInfo{}, false
|
||
}
|
||
|
||
func localLunarEclipseInfoFromBasic(
|
||
result basic.LunarEclipseResult,
|
||
lon, lat, height float64,
|
||
location *time.Location,
|
||
) LocalLunarEclipseInfo {
|
||
maximum := ttJDEToTime(result.Maximum, location)
|
||
visibleThreshold := localLunarEclipseVisibilityThreshold(height, lat)
|
||
moonAltitude := lunarAltitude(maximum, lon, lat)
|
||
saros, hasSaros := lunarSarosInfo(result.Maximum)
|
||
|
||
return LocalLunarEclipseInfo{
|
||
HasSaros: hasSaros,
|
||
Saros: saros,
|
||
Type: mapBasicLunarEclipseType(result.Type),
|
||
Longitude: lon,
|
||
Latitude: lat,
|
||
Height: height,
|
||
PenumbralMagnitude: result.PenumbralMagnitude,
|
||
UmbralMagnitude: result.Magnitude,
|
||
PenumbralStart: ttJDEToTime(result.PenumbralStart, location),
|
||
PartialStart: ttJDEToTime(result.PartialStart, location),
|
||
TotalStart: ttJDEToTime(result.TotalStart, location),
|
||
Maximum: maximum,
|
||
TotalEnd: ttJDEToTime(result.TotalEnd, location),
|
||
PartialEnd: ttJDEToTime(result.PartialEnd, location),
|
||
PenumbralEnd: ttJDEToTime(result.PenumbralEnd, location),
|
||
MoonAltitude: moonAltitude,
|
||
MoonAzimuth: lunarAzimuth(maximum, lon, lat),
|
||
VisibleAtMaximum: moonAltitude > visibleThreshold,
|
||
HasPenumbral: result.HasPenumbral,
|
||
HasPartial: result.HasPartial,
|
||
HasTotal: result.HasTotal,
|
||
}
|
||
}
|
||
|
||
func localLunarEclipseOverlapsDate(info LocalLunarEclipseInfo, dayStart, dayEnd time.Time) bool {
|
||
eventStart, eventEnd, ok := localLunarEclipseRange(info)
|
||
if !ok {
|
||
return false
|
||
}
|
||
return !eventEnd.Before(dayStart) && eventStart.Before(dayEnd)
|
||
}
|
||
|
||
func localLunarEclipseRange(info LocalLunarEclipseInfo) (time.Time, time.Time, bool) {
|
||
if !info.HasPenumbral {
|
||
return time.Time{}, time.Time{}, false
|
||
}
|
||
return info.PenumbralStart, info.PenumbralEnd, true
|
||
}
|
||
|
||
func localLunarEclipseVisible(info LocalLunarEclipseInfo) bool {
|
||
eventStart, eventEnd, ok := localLunarEclipseRange(info)
|
||
if !ok {
|
||
return false
|
||
}
|
||
return localLunarEclipseVisibleDuring(info, eventStart, eventEnd)
|
||
}
|
||
|
||
func localTotalLunarEclipseVisible(info LocalLunarEclipseInfo) bool {
|
||
if !info.HasTotal || info.TotalStart.IsZero() || info.TotalEnd.IsZero() {
|
||
return false
|
||
}
|
||
return localLunarEclipseVisibleDuring(info, info.TotalStart, info.TotalEnd)
|
||
}
|
||
|
||
func localLunarEclipseVisibleOnDate(info LocalLunarEclipseInfo, dayStart, dayEnd time.Time) bool {
|
||
eventStart, eventEnd, ok := localLunarEclipseRange(info)
|
||
if !ok {
|
||
return false
|
||
}
|
||
segmentStart := maxLocalLunarTime(eventStart, dayStart)
|
||
segmentEnd := minLocalLunarTime(eventEnd, dayEnd)
|
||
if !segmentStart.Before(segmentEnd) {
|
||
return false
|
||
}
|
||
return localLunarEclipseVisibleDuring(info, segmentStart, segmentEnd)
|
||
}
|
||
|
||
func localLunarEclipseVisibleDuring(info LocalLunarEclipseInfo, start, end time.Time) bool {
|
||
if localLunarEclipseAltitudeVisible(start, info) || localLunarEclipseAltitudeVisible(end, info) {
|
||
return true
|
||
}
|
||
|
||
for dayStart, _, _ := lunarEclipseLocalDayBounds(start); !dayStart.After(end); dayStart = nextLunarEclipseLocalDayStart(dayStart) {
|
||
_, culminationSeed, _ := lunarEclipseLocalDayBounds(dayStart)
|
||
culmination := lunarCulminationTime(culminationSeed, info.Longitude, info.Latitude)
|
||
if culmination.Before(start) || culmination.After(end) {
|
||
continue
|
||
}
|
||
if localLunarEclipseAltitudeVisible(culmination, info) {
|
||
return true
|
||
}
|
||
}
|
||
|
||
return false
|
||
}
|
||
|
||
func localLunarEclipseAltitudeVisible(date time.Time, info LocalLunarEclipseInfo) bool {
|
||
return lunarAltitude(date, info.Longitude, info.Latitude) > localLunarEclipseVisibilityThreshold(info.Height, info.Latitude)
|
||
}
|
||
|
||
func localLunarEclipseVisibilityThreshold(height, latitude float64) float64 {
|
||
if height <= 0 {
|
||
return 0
|
||
}
|
||
return -basic.HeightDegreeByLat(height, latitude)
|
||
}
|
||
|
||
func maxLocalLunarTime(a, b time.Time) time.Time {
|
||
if a.After(b) {
|
||
return a
|
||
}
|
||
return b
|
||
}
|
||
|
||
func minLocalLunarTime(a, b time.Time) time.Time {
|
||
if a.Before(b) {
|
||
return a
|
||
}
|
||
return b
|
||
}
|