245 lines
10 KiB
Go
245 lines
10 KiB
Go
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package basic
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import (
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"math"
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"testing"
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"time"
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)
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func TestOccultationRiseSetVectorStateMatchesLegacyTopocentricState(t *testing.T) {
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planetConfig, ok := planetOccultationConfigFor(OccultationSaturn)
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if !ok {
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t.Fatal("Saturn occultation config is unavailable")
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}
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planetTT := occultationTimeToTT(time.Date(2024, time.August, 21, 2, 41, 36, 0, time.UTC))
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planetState := planetOccultationEphemerisStateAt(planetTT, planetConfig)
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star := StarCoordinate{
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ID: "parallax-test", RA: 247.3516666666667, Dec: -26.431944444444444,
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Epoch: time.Date(2000, 1, 1, 12, 0, 0, 0, time.UTC), Frame: CoordinateFrameJ2000,
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ProperMotionRACosDecMasPerYear: -10, ProperMotionDecMasPerYear: -20, ParallaxMas: 24,
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}
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starTT := occultationTimeToTT(time.Date(2026, time.February, 11, 12, 0, 0, 0, time.UTC))
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starState := starOccultationEphemerisStateAt(starTT, star)
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contexts := []struct {
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name string
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tt float64
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moonRA, moonDec, moonDistanceKM float64
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targetRA, targetDec, targetDistanceKM float64
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targetRadiusKM float64
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}{
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{
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name: "planet", tt: planetTT,
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moonRA: planetState.moonRA, moonDec: planetState.moonDec, moonDistanceKM: planetState.moonDistanceKM,
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targetRA: planetState.planetRA, targetDec: planetState.planetDec, targetDistanceKM: planetState.planetDistanceKM,
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targetRadiusKM: planetConfig.equatorialRadiusKM,
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},
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{
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name: "finite-distance-star", tt: starTT,
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moonRA: starState.moonRA, moonDec: starState.moonDec, moonDistanceKM: starState.moonDistanceKM,
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targetRA: starState.starRA, targetDec: starState.starDec, targetDistanceKM: starState.starDistanceKM,
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},
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{
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name: "infinite-distance-star", tt: starTT,
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moonRA: starState.moonRA, moonDec: starState.moonDec, moonDistanceKM: starState.moonDistanceKM,
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targetRA: starState.starRA, targetDec: starState.starDec,
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},
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}
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locations := []Observer{
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{Longitude: 0, Latitude: 0},
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{Longitude: 115.4, Latitude: 32.9},
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{Longitude: -73.9857, Latitude: 40.7484},
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{Longitude: 179.9, Latitude: 80},
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{Longitude: -120, Latitude: -70},
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}
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for _, test := range contexts {
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t.Run(test.name, func(t *testing.T) {
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context := newOccultationRiseSetContext(
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test.tt, test.moonRA, test.moonDec, test.moonDistanceKM,
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test.targetRA, test.targetDec, test.targetDistanceKM, test.targetRadiusKM,
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)
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for _, observer := range locations {
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got := context.stateAt(observer.Longitude, observer.Latitude)
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want := legacyOccultationRiseSetStateAt(
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test.tt, test.moonRA, test.moonDec, test.moonDistanceKM,
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test.targetRA, test.targetDec, test.targetDistanceKM, test.targetRadiusKM,
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observer.Longitude, observer.Latitude,
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)
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if got.valid != want.valid {
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t.Fatalf("observer %.4f %.4f valid=%t, want %t", observer.Longitude, observer.Latitude, got.valid, want.valid)
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}
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if !got.valid {
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continue
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}
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assertOccultationRiseSetStateClose(t, "contact metric", got.contactMetric, want.contactMetric, 2e-10)
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assertOccultationRiseSetStateClose(t, "separation squared", got.separationSquared, want.separationSquared, 2e-13)
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assertOccultationRiseSetStateClose(t, "moon altitude", got.moonAltitude, want.moonAltitude, 2e-10)
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}
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})
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}
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}
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func TestOccultationRiseSetContextFromVectorsMatchesRADecContext(t *testing.T) {
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config, ok := planetOccultationConfigFor(OccultationSaturn)
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if !ok {
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t.Fatal("Saturn occultation config is unavailable")
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}
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tt := occultationTimeToTT(time.Date(2025, time.January, 5, 17, 0, 0, 0, time.UTC))
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state := planetOccultationEphemerisStateAt(tt, config)
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moon := occultationPathRaDecVector(state.moonRA, state.moonDec, state.moonDistanceKM)
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target := occultationPathRaDecVector(state.planetRA, state.planetDec, state.planetDistanceKM)
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vectorContext := newOccultationRiseSetContextFromVectors(
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tt,
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[3]float64{moon.x, moon.y, moon.z},
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[3]float64{target.x, target.y, target.z},
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true,
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config.equatorialRadiusKM,
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)
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raDecContext := newOccultationRiseSetContext(
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tt, state.moonRA, state.moonDec, state.moonDistanceKM,
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state.planetRA, state.planetDec, state.planetDistanceKM, config.equatorialRadiusKM,
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)
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for _, observer := range []Observer{
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{Longitude: 0, Latitude: 0},
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{Longitude: 115.4, Latitude: 32.9},
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{Longitude: -45, Latitude: 82},
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{Longitude: 170, Latitude: -70},
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} {
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got := vectorContext.stateAt(observer.Longitude, observer.Latitude)
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want := raDecContext.stateAt(observer.Longitude, observer.Latitude)
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if got.valid != want.valid {
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t.Fatalf("observer %.3f %.3f valid=%t, want %t", observer.Longitude, observer.Latitude, got.valid, want.valid)
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}
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if !got.valid {
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continue
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}
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assertOccultationRiseSetStateClose(t, "contact metric", got.contactMetric, want.contactMetric, 1e-12)
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assertOccultationRiseSetStateClose(t, "separation squared", got.separationSquared, want.separationSquared, 1e-15)
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assertOccultationRiseSetStateClose(t, "moon altitude", got.moonAltitude, want.moonAltitude, 1e-12)
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}
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}
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func TestOccultationRiseSetMoonHorizonResidualMatchesVectorAltitude(t *testing.T) {
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config, ok := planetOccultationConfigFor(OccultationSaturn)
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if !ok {
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t.Fatal("Saturn occultation config is unavailable")
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}
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tt := occultationTimeToTT(time.Date(2025, time.January, 5, 17, 0, 0, 0, time.UTC))
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state := planetOccultationEphemerisStateAt(tt, config)
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context := newOccultationRiseSetContext(
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tt, state.moonRA, state.moonDec, state.moonDistanceKM,
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state.planetRA, state.planetDec, state.planetDistanceKM, config.equatorialRadiusKM,
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)
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for _, observer := range []Observer{
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{Longitude: 0, Latitude: 0},
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{Longitude: 115.4, Latitude: 32.9},
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{Longitude: -45, Latitude: 82},
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{Longitude: 170, Latitude: -70},
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} {
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got, valid := context.moonHorizonResidual(observer.Longitude, observer.Latitude)
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observerParallax, _, zenith := occultationRiseSetObserverVectors(
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context.siderealDegrees, observer.Longitude, observer.Latitude,
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)
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topocentricMoon := occultationPathSub(context.moon.positionKM, observerParallax)
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want := occultationPathDot(topocentricMoon, zenith)
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if !valid || math.Abs(got-want) > 1e-8 {
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t.Fatalf("observer %.3f %.3f horizon residual=%.15g valid=%t, want %.15g",
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observer.Longitude, observer.Latitude, got, valid, want)
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}
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altitude := context.stateAt(observer.Longitude, observer.Latitude).moonAltitude * rad
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if difference := math.Abs(got/occultationPathNorm(topocentricMoon) - math.Sin(altitude)); difference > 1e-14 {
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t.Fatalf("observer %.3f %.3f normalized horizon residual differs by %.3g",
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observer.Longitude, observer.Latitude, difference)
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}
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}
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}
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func TestOccultationRiseSetEvaluationCacheSeparatesCandidateAndExactContexts(t *testing.T) {
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var exactCalls, candidateCalls int
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contextAt := func(tt float64) occultationRiseSetContext {
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return newOccultationRiseSetContext(tt, 10, 5, 384000, 10.5, 5.25, 1e9, 0)
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}
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cache := newOccultationRiseSetEvaluationCacheWithCandidate(
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func(tt float64) occultationRiseSetContext {
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exactCalls++
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return contextAt(tt)
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},
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func(tt float64) occultationRiseSetContext {
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candidateCalls++
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return contextAt(tt)
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},
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)
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tt := occultationTimeToTT(time.Date(2025, time.January, 5, 17, 0, 0, 0, time.UTC))
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cache.candidateEvaluation(tt)
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cache.candidateEvaluation(tt)
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if exactCalls != 0 || candidateCalls != 3 {
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t.Fatalf("candidate evaluation calls exact=%d candidate=%d, want 0/3", exactCalls, candidateCalls)
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}
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cache.evaluation(tt)
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cache.evaluation(tt)
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if exactCalls != 3 || candidateCalls != 3 {
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t.Fatalf("exact evaluation calls exact=%d candidate=%d, want 3/3", exactCalls, candidateCalls)
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}
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}
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func legacyOccultationRiseSetStateAt(
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tt, moonRA, moonDec, moonDistanceKM,
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targetRA, targetDec, targetDistanceKM, targetRadiusKM,
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longitude, latitude float64,
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) occultationRiseSetState {
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siderealDegrees := ApparentSiderealTime(TD2UT(tt, false)) * 15
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observer := Observer{Longitude: longitude, Latitude: latitude}
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moonTopocentricRA, moonTopocentricDec := topocentricRaDecWithSidereal(
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moonRA, moonDec, latitude, longitude, siderealDegrees,
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moonDistanceKM/occultationPathAstronomicalUnitKM, 0,
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)
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moonTopocentricRA = normalizeRA(moonTopocentricRA)
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targetTopocentricRA, targetTopocentricDec := targetRA, targetDec
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if targetDistanceKM > 0 {
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targetTopocentricRA, targetTopocentricDec = topocentricRaDecWithSidereal(
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targetRA, targetDec, latitude, longitude, siderealDegrees,
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targetDistanceKM/occultationPathAstronomicalUnitKM, 0,
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)
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targetTopocentricRA = normalizeRA(targetTopocentricRA)
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}
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moonTopocentricDistanceKM := topocentricDistanceKMWithSidereal(
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moonRA, moonDec, moonDistanceKM, observer, siderealDegrees,
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)
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if !finite(moonTopocentricDistanceKM) || moonTopocentricDistanceKM <= moonEquatorialRadiusKM {
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return occultationRiseSetState{}
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}
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moonRadius := angularSemidiameterArcsec(moonEquatorialRadiusKM, moonTopocentricDistanceKM) / 3600
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targetRadius := 0.0
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if targetRadiusKM > 0 {
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targetTopocentricDistanceKM := topocentricDistanceKMWithSidereal(
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targetRA, targetDec, targetDistanceKM, observer, siderealDegrees,
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)
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if !finite(targetTopocentricDistanceKM) || targetTopocentricDistanceKM <= targetRadiusKM {
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return occultationRiseSetState{}
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}
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targetRadius = angularSemidiameterArcsec(targetRadiusKM, targetTopocentricDistanceKM) / 3600
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}
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separation := angularSeparationDegrees(
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moonTopocentricRA, moonTopocentricDec, targetTopocentricRA, targetTopocentricDec,
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)
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separationRad := separation * rad
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moonAltitude := occultationAltitudeWithSidereal(
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siderealDegrees, observer, moonTopocentricRA, moonTopocentricDec,
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)
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return occultationRiseSetState{
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contactMetric: separation - moonRadius - targetRadius,
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separationSquared: 2 - 2*math.Cos(separationRad),
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moonAltitude: moonAltitude,
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valid: finite(separation) && finite(moonRadius) && finite(targetRadius) && finite(moonAltitude),
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}
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}
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func assertOccultationRiseSetStateClose(t *testing.T, name string, got, want, tolerance float64) {
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t.Helper()
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if difference := math.Abs(got - want); difference > tolerance {
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t.Fatalf("%s=%.15g, want %.15g (difference %.3g, tolerance %.3g)", name, got, want, difference, tolerance)
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}
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}
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