feat: 新增月掩与日月食地理绘图并提升观测计算精度
- 新增月掩恒星和行星：支持搜索、掩甚点、全球掩带及固定地点轨迹计算 - 支持恒星星表坐标转换、有限盘面行星接触事件和月掩 SVG 输出 - 新增日月食及月掩全球投影图、时间标记和 GeoJSON 地理数据接口 - 扩展日食中心线、南北界及偏食足迹采样，支持极区投影 - 修正站心时角、月出月落、月球视半径、折射和恒星自行计算 - 优化内外行星事件搜索、边界选择、极端输入处理和计算稳定性
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package basic
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import (
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"math"
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"sort"
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)
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const (
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planetOccultationDiagramDefaultStepDays = 2.0 / 1440.0
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planetOccultationDiagramMinStepDays = 1.0 / 86400.0
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planetOccultationDiagramMaxSamples = 2000
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planetOccultationDiagramDuplicateDays = 1e-10
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planetOccultationDiagramGeometryArcsec = 0.05
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planetOccultationDiagramPositionDeg = 0.01
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planetOccultationDiagramContactTimeDays = 1e-6
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)
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// PlanetOccultationDiagramOptions 控制本地行星月掩轨迹采样。
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// PlanetOccultationDiagramOptions controls local planetary-occultation track sampling.
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type PlanetOccultationDiagramOptions struct {
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// StepDays 是请求的轨迹采样步长，单位为日；非正值或非有限值使用两分钟，正值小于一秒时使用一秒。长事件可能增大实际步长，使基础轨迹不超过 2000 个采样点；必要阶段帧仍会额外保留。结果会报告实际采用的值。
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// StepDays is the requested track sampling step in days. Non-positive or non-finite values use two minutes, and positive values below one second use one second. Long events may increase the effective step to keep the base track within 2000 samples; required phase frames are retained in addition. The result reports the effective value.
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StepDays float64
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}
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// PlanetOccultationDiagramFrame 描述一个时刻的站心月球与行星几何。
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// PlanetOccultationDiagramFrame describes topocentric Moon-planet geometry at one instant.
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type PlanetOccultationDiagramFrame struct {
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// JDE 是 TT 儒略历书日。
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// JDE is the TT Julian ephemeris day.
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JDE float64
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// PlanetXArcsec 和 PlanetYArcsec 是相对月心的切平面偏移，单位为角秒。X 向东为正，Y 向北为正。
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// PlanetXArcsec and PlanetYArcsec are tangent-plane offsets from the lunar center. X is positive east and Y is positive north.
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PlanetXArcsec float64
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PlanetYArcsec float64
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// MoonRadiusArcsec 和 PlanetRadiusArcsec 是站心视半径，单位为角秒。
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// MoonRadiusArcsec and PlanetRadiusArcsec are topocentric apparent semidiameters.
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MoonRadiusArcsec float64
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PlanetRadiusArcsec float64
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// SeparationArcsec 和 PositionAngleDeg 描述行星中心相对月心的位置。
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// SeparationArcsec and PositionAngleDeg describe the planet center relative to the lunar center.
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SeparationArcsec float64
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PositionAngleDeg float64
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// MoonAltitudeDeg 和 MoonAzimuthDeg 是站心地平坐标。
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// MoonAltitudeDeg and MoonAzimuthDeg are topocentric horizontal coordinates.
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MoonAltitudeDeg float64
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MoonAzimuthDeg float64
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// DisksOverlap 表示两个视盘面存在正面积交集。
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// DisksOverlap is true while the two apparent disks have a positive-area intersection.
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DisksOverlap bool
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// FullyOcculted 表示行星盘面完全位于月缘内侧。
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// FullyOcculted is true while the planet disk lies strictly inside the lunar limb.
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FullyOcculted bool
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// Label 是主阶段标识；Labels 在掠掩事件中保留重合阶段。
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// Label is the primary key phase; Labels retains coincident phases for grazing events.
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Label string
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Labels []string
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}
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// PlanetOccultationDiagramResult 包含固定地点行星月掩的几何数据。
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// PlanetOccultationDiagramResult contains geometry for a fixed-site planetary occultation.
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type PlanetOccultationDiagramResult struct {
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Occultation PlanetOccultationInfo
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Frames []PlanetOccultationDiagramFrame
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// StepDays 是实际采用的基础轨迹采样步长，单位为日。
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// StepDays is the effective base-track sampling step in days.
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StepDays float64
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}
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type planetOccultationDiagramTime struct {
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jde float64
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labels []string
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}
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// PlanetOccultationDiagram 为已求解的固定地点行星月掩计算以月心为原点的切平面轨迹。事件数据无效或不完整时，结果不含帧。
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// PlanetOccultationDiagram computes a Moon-centered tangent-plane track for an already solved fixed-site planetary occultation. Invalid or incomplete event data produces a result without frames.
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func PlanetOccultationDiagram(
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info PlanetOccultationInfo,
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options PlanetOccultationDiagramOptions,
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) PlanetOccultationDiagramResult {
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options = normalizePlanetOccultationDiagramOptions(options)
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result := PlanetOccultationDiagramResult{Occultation: info, StepDays: options.StepDays}
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if !planetOccultationDiagramInputValid(info) {
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return result
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}
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config, ok := planetOccultationConfigFor(info.Planet)
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if !ok {
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return result
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}
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startTT := occultationTimeToTT(info.ExternalImmersion)
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greatestTT := occultationTimeToTT(info.Greatest)
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endTT := occultationTimeToTT(info.ExternalEmersion)
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externalImmersionFrame, externalImmersionOK := planetOccultationDiagramFrameAt(startTT, config, info.Observer)
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greatestFrame, greatestOK := planetOccultationDiagramFrameAt(greatestTT, config, info.Observer)
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externalEmersionFrame, externalEmersionOK := planetOccultationDiagramFrameAt(endTT, config, info.Observer)
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if !externalImmersionOK || !greatestOK || !externalEmersionOK {
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return result
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}
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var (
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internalImmersionFrame, internalEmersionFrame PlanetOccultationDiagramFrame
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internalImmersionOK, internalEmersionOK bool
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)
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if info.HasInternalContacts {
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internalImmersionFrame, internalImmersionOK = planetOccultationDiagramFrameAt(
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occultationTimeToTT(info.InternalImmersion), config, info.Observer,
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)
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internalEmersionFrame, internalEmersionOK = planetOccultationDiagramFrameAt(
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occultationTimeToTT(info.InternalEmersion), config, info.Observer,
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)
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}
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if (info.HasInternalContacts && (!internalImmersionOK || !internalEmersionOK)) ||
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!planetOccultationDiagramMatchesInfo(
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info, startTT, greatestTT, endTT,
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externalImmersionFrame, internalImmersionFrame, greatestFrame, internalEmersionFrame, externalEmersionFrame,
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) {
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return result
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}
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times, stepDays := planetOccultationDiagramTimes(info, startTT, greatestTT, endTT, options.StepDays)
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result.StepDays = stepDays
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result.Frames = make([]PlanetOccultationDiagramFrame, 0, len(times))
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for _, item := range times {
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frame, frameOK := planetOccultationDiagramFrameAt(item.jde, config, info.Observer)
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if !frameOK {
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return PlanetOccultationDiagramResult{Occultation: info, StepDays: stepDays}
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}
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frame.Labels = append([]string(nil), item.labels...)
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frame.Label = planetOccultationDiagramPrimaryLabel(item.labels)
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result.Frames = append(result.Frames, frame)
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}
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return result
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}
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func planetOccultationDiagramMatchesInfo(
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info PlanetOccultationInfo,
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startTT, greatestTT, endTT float64,
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externalImmersion, internalImmersion, greatest, internalEmersion, externalEmersion PlanetOccultationDiagramFrame,
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) bool {
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if !finite(info.MinimumSeparationArcsec) || info.MinimumSeparationArcsec < 0 ||
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!finite(info.PositionAngleDeg) ||
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!finite(info.MoonSemidiameterArcsec) || info.MoonSemidiameterArcsec <= 0 ||
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!finite(info.PlanetSemidiameterArcsec) || info.PlanetSemidiameterArcsec <= 0 {
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return false
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}
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if math.Abs(externalImmersion.SeparationArcsec-externalImmersion.MoonRadiusArcsec-externalImmersion.PlanetRadiusArcsec) > planetOccultationDiagramGeometryArcsec ||
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math.Abs(externalEmersion.SeparationArcsec-externalEmersion.MoonRadiusArcsec-externalEmersion.PlanetRadiusArcsec) > planetOccultationDiagramGeometryArcsec {
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return false
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}
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if math.Abs(greatest.SeparationArcsec-info.MinimumSeparationArcsec) > planetOccultationDiagramGeometryArcsec ||
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math.Abs(greatest.MoonRadiusArcsec-info.MoonSemidiameterArcsec) > planetOccultationDiagramGeometryArcsec ||
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math.Abs(greatest.PlanetRadiusArcsec-info.PlanetSemidiameterArcsec) > planetOccultationDiagramGeometryArcsec ||
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math.Abs(signedAngleDifference(greatest.PositionAngleDeg, info.PositionAngleDeg)) > planetOccultationDiagramPositionDeg {
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return false
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}
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externalMetric := greatest.SeparationArcsec - greatest.MoonRadiusArcsec - greatest.PlanetRadiusArcsec
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internalMetric := greatest.SeparationArcsec - greatest.MoonRadiusArcsec + greatest.PlanetRadiusArcsec
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switch info.Type {
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case OccultationPartial:
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return externalMetric < -planetOccultationGrazingToleranceArcsec &&
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internalMetric >= -planetOccultationGrazingToleranceArcsec
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case OccultationGrazing:
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return math.Abs(externalMetric) <= planetOccultationGrazingToleranceArcsec &&
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math.Abs(startTT-greatestTT) <= planetOccultationDiagramContactTimeDays &&
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math.Abs(endTT-greatestTT) <= planetOccultationDiagramContactTimeDays
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case OccultationTotal:
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if math.Abs(internalImmersion.SeparationArcsec-internalImmersion.MoonRadiusArcsec+internalImmersion.PlanetRadiusArcsec) > planetOccultationDiagramGeometryArcsec ||
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math.Abs(internalEmersion.SeparationArcsec-internalEmersion.MoonRadiusArcsec+internalEmersion.PlanetRadiusArcsec) > planetOccultationDiagramGeometryArcsec {
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return false
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}
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return externalMetric < -planetOccultationGrazingToleranceArcsec &&
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internalMetric < -planetOccultationGrazingToleranceArcsec
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default:
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return false
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}
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}
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func normalizePlanetOccultationDiagramOptions(options PlanetOccultationDiagramOptions) PlanetOccultationDiagramOptions {
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if options.StepDays <= 0 || !finite(options.StepDays) {
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options.StepDays = planetOccultationDiagramDefaultStepDays
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}
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if options.StepDays < planetOccultationDiagramMinStepDays {
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options.StepDays = planetOccultationDiagramMinStepDays
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}
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return options
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}
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func planetOccultationDiagramInputValid(info PlanetOccultationInfo) bool {
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if info.Planet.Validate() != nil || info.Observer.Validate() != nil || !info.ContactsComplete ||
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info.ExternalImmersion.IsZero() || info.Greatest.IsZero() || info.ExternalEmersion.IsZero() ||
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info.Greatest.Before(info.ExternalImmersion) || info.ExternalEmersion.Before(info.Greatest) {
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return false
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}
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switch info.Type {
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case OccultationTotal:
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return info.HasInternalContacts && !info.InternalImmersion.IsZero() && !info.InternalEmersion.IsZero() &&
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info.InternalImmersion.After(info.ExternalImmersion) && info.InternalImmersion.Before(info.Greatest) &&
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info.InternalEmersion.After(info.Greatest) && info.InternalEmersion.Before(info.ExternalEmersion)
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case OccultationPartial:
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return !info.HasInternalContacts && info.InternalImmersion.IsZero() && info.InternalEmersion.IsZero()
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case OccultationGrazing:
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return !info.HasInternalContacts && info.InternalImmersion.IsZero() && info.InternalEmersion.IsZero()
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default:
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return false
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}
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}
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func planetOccultationDiagramTimes(
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info PlanetOccultationInfo,
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startTT, greatestTT, endTT, stepDays float64,
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) ([]planetOccultationDiagramTime, float64) {
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if !finite(startTT) || !finite(greatestTT) || !finite(endTT) || greatestTT < startTT || endTT < greatestTT {
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return nil, stepDays
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}
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if endTT > startTT {
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if sampleCount := int(math.Ceil((endTT-startTT)/stepDays)) + 1; sampleCount > planetOccultationDiagramMaxSamples {
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stepDays = (endTT - startTT) / float64(planetOccultationDiagramMaxSamples-1)
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}
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}
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times := []planetOccultationDiagramTime{
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{jde: startTT, labels: []string{"C1"}},
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{jde: greatestTT, labels: []string{"Greatest"}},
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{jde: endTT, labels: []string{"C4"}},
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}
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if info.HasInternalContacts {
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times = append(times,
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planetOccultationDiagramTime{jde: occultationTimeToTT(info.InternalImmersion), labels: []string{"C2"}},
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planetOccultationDiagramTime{jde: occultationTimeToTT(info.InternalEmersion), labels: []string{"C3"}},
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)
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}
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for jde := startTT + stepDays; jde < endTT; jde += stepDays {
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times = append(times, planetOccultationDiagramTime{jde: jde})
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}
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sort.SliceStable(times, func(i, j int) bool {
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if times[i].jde == times[j].jde {
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return planetOccultationDiagramLabelPriority(times[i].labels) < planetOccultationDiagramLabelPriority(times[j].labels)
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}
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return times[i].jde < times[j].jde
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})
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return uniquePlanetOccultationDiagramTimes(times), stepDays
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}
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func uniquePlanetOccultationDiagramTimes(times []planetOccultationDiagramTime) []planetOccultationDiagramTime {
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unique := times[:0]
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for _, item := range times {
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if !finite(item.jde) {
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continue
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}
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if len(unique) == 0 || math.Abs(item.jde-unique[len(unique)-1].jde) > planetOccultationDiagramDuplicateDays {
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item.labels = append([]string(nil), item.labels...)
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unique = append(unique, item)
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continue
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}
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unique[len(unique)-1].labels = mergeStarOccultationDiagramLabels(unique[len(unique)-1].labels, item.labels)
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}
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return unique
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}
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func planetOccultationDiagramPrimaryLabel(labels []string) string {
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for _, label := range labels {
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if label == "Greatest" {
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return label
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}
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}
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if len(labels) == 0 {
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return ""
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}
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return labels[0]
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}
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func planetOccultationDiagramLabelPriority(labels []string) int {
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if len(labels) == 0 {
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return 99
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}
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switch labels[0] {
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case "C1":
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return 0
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case "C2":
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return 1
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case "Greatest":
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return 2
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case "C3":
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return 3
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case "C4":
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return 4
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default:
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return 99
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}
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}
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func planetOccultationDiagramFrameAt(
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tt float64,
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config planetOccultationConfig,
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observer Observer,
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) (PlanetOccultationDiagramFrame, bool) {
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state := planetOccultationStateAt(tt, config, &observer, -1)
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if !state.valid {
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return PlanetOccultationDiagramFrame{}, false
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}
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positionAngle := occultationPositionAngle(
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state.position.moonRA, state.position.moonDec,
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state.position.planetRA, state.position.planetDec,
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)
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if !finite(positionAngle) {
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return PlanetOccultationDiagramFrame{}, false
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}
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angle := positionAngle * math.Pi / 180
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return PlanetOccultationDiagramFrame{
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JDE: tt,
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PlanetXArcsec: state.separationArcsec * math.Sin(angle),
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PlanetYArcsec: state.separationArcsec * math.Cos(angle),
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MoonRadiusArcsec: state.moonSemidiameter,
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PlanetRadiusArcsec: state.planetSemidiameter,
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SeparationArcsec: state.separationArcsec,
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PositionAngleDeg: positionAngle,
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MoonAltitudeDeg: occultationAltitude(tt, observer, state.position.moonRA, state.position.moonDec),
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MoonAzimuthDeg: occultationAzimuth(tt, observer, state.position.moonRA, state.position.moonDec),
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DisksOverlap: state.externalContactMetric < -planetOccultationGrazingToleranceArcsec,
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FullyOcculted: state.internalContactMetric < -planetOccultationGrazingToleranceArcsec,
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}, true
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}
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Block a user