mirror of
https://github.com/acamarata/moon-sighting.git
synced 2026-06-30 19:04:24 +00:00
style: fix prettier table formatting in wiki
This commit is contained in:
Aric Camarata
parent
0bf9e6eb16
commit
b032fb596f
10 changed files with 184 additions and 170 deletions
|
|
@ -120,7 +120,7 @@ function getMoonPosition(
|
|||
**Parameters:**
|
||||
|
||||
| Parameter | Type | Description |
|
||||
| --------- | ---- | ----------- |
|
||||
| ----------- | --------- | ------------------------------------------- |
|
||||
| `date` | `Date?` | Date to evaluate. Defaults to now |
|
||||
| `lat` | `number` | Geodetic latitude, degrees (north positive) |
|
||||
| `lon` | `number` | Longitude, degrees (east positive) |
|
||||
|
|
@ -161,7 +161,7 @@ function getMoonIllumination(date?: Date): MoonIlluminationResult
|
|||
**Parameters:**
|
||||
|
||||
| Parameter | Type | Description |
|
||||
| --------- | ---- | ----------- |
|
||||
| --------- | ------- | --------------------------------- |
|
||||
| `date` | `Date?` | Date to evaluate. Defaults to now |
|
||||
|
||||
**MoonIlluminationResult:**
|
||||
|
|
@ -233,7 +233,7 @@ function getMoonVisibilityEstimate(
|
|||
**Parameters:**
|
||||
|
||||
| Parameter | Type | Description |
|
||||
| --------- | ---- | ----------- |
|
||||
| ----------- | --------- | -------------------------------------------------------------------------------- |
|
||||
| `date` | `Date?` | Observation time. Defaults to now. Use a post-sunset time for meaningful results |
|
||||
| `lat` | `number` | Geodetic latitude, degrees (north positive) |
|
||||
| `lon` | `number` | Longitude, degrees (east positive) |
|
||||
|
|
@ -275,12 +275,7 @@ console.log(est.isVisibleNakedEye) // true/false
|
|||
Combined kernel-free snapshot: phase, position, illumination, and visibility estimate in one call.
|
||||
|
||||
```ts
|
||||
function getMoon(
|
||||
date?: Date,
|
||||
lat: number,
|
||||
lon: number,
|
||||
elevation?: number,
|
||||
): MoonSnapshot
|
||||
function getMoon(date?: Date, lat: number, lon: number, elevation?: number): MoonSnapshot
|
||||
```
|
||||
|
||||
**MoonSnapshot:**
|
||||
|
|
@ -434,4 +429,4 @@ ODEH_DESCRIPTIONS // Record<OdehZone, string>
|
|||
|
||||
---
|
||||
|
||||
*Previous: [Home](Home) | Next: [Architecture](Architecture)*
|
||||
_Previous: [Home](Home) | Next: [Architecture](Architecture)_
|
||||
|
|
|
|||
|
|
@ -124,7 +124,7 @@ Target: a full sighting report (sunset + moonset + best-time geometry + Yallop +
|
|||
A crescent sighting report's accuracy is limited by the worst source in the chain:
|
||||
|
||||
| Source | Contribution |
|
||||
| ------ | ------------ |
|
||||
| -------------------------------------------------- | --------------------------------------- |
|
||||
| DE442S position error | < 1 km (~0.001 arcsec at Moon distance) |
|
||||
| IERS Q·R·W transform (with user-supplied EOP) | < 1 mas |
|
||||
| IERS Q·R·W transform (polynomial ΔT approximation) | < 5 arcsec |
|
||||
|
|
@ -136,4 +136,4 @@ In practice, refraction uncertainty dominates all other error sources for cresce
|
|||
|
||||
---
|
||||
|
||||
*Previous: [API Reference](API-Reference) | Next: [Crescent Visibility](Crescent-Visibility)*
|
||||
_Previous: [API Reference](API-Reference) | Next: [Crescent Visibility](Crescent-Visibility)_
|
||||
|
|
|
|||
|
|
@ -49,7 +49,7 @@ This polynomial represents the minimum ARCV observed in historical crescent sigh
|
|||
### Categories
|
||||
|
||||
| Category | q range | Meaning |
|
||||
| -------- | ------- | ------- |
|
||||
| -------- | ---------- | -------------------------------------------------- |
|
||||
| A | q > +0.216 | Easily visible to the naked eye |
|
||||
| B | q > −0.014 | Visible under perfect conditions |
|
||||
| C | q > −0.160 | May need optical aid to locate; naked eye possible |
|
||||
|
|
@ -88,7 +88,7 @@ V = ARCV - (11.8371 - 6.3226·W + 0.7319·W² - 0.1018·W³)
|
|||
### Zones
|
||||
|
||||
| Zone | V range | Meaning |
|
||||
| ---- | ------- | ------- |
|
||||
| ---- | --------- | --------------------------------------------------------------------- |
|
||||
| A | V ≥ 5.65 | Visible with naked eye |
|
||||
| B | V ≥ 2.00 | Visible with optical aid; may be naked eye under excellent conditions |
|
||||
| C | V ≥ −0.96 | Visible with optical aid only |
|
||||
|
|
@ -146,4 +146,4 @@ This approach requires additional atmospheric inputs (aerosol optical depth, hum
|
|||
|
||||
---
|
||||
|
||||
*Previous: [Architecture](Architecture) | Next: [Ephemeris](Ephemeris)*
|
||||
_Previous: [Architecture](Architecture) | Next: [Ephemeris](Ephemeris)_
|
||||
|
|
|
|||
|
|
@ -60,6 +60,7 @@ Each record covers a fixed time interval and stores coefficients for X, Y, Z:
|
|||
```
|
||||
|
||||
The polynomial degree n is derived from RSIZE (record size in doubles):
|
||||
|
||||
```
|
||||
n = (RSIZE - 2) / 3 - 1
|
||||
```
|
||||
|
|
@ -93,6 +94,7 @@ result = c_0 + x·b_1 - b_2
|
|||
This produces the position. Velocity requires the derivative d(result)/dt, computed via the Chebyshev derivative recurrence, not by finite differencing, which would lose accuracy.
|
||||
|
||||
Transforming from normalized domain back to physical time:
|
||||
|
||||
```
|
||||
x = (et - MID) / RADIUS
|
||||
dx/dt = 1/RADIUS
|
||||
|
|
@ -152,4 +154,4 @@ See [Validation](Validation) for the test methodology.
|
|||
|
||||
---
|
||||
|
||||
*Previous: [Crescent Visibility](Crescent-Visibility) | Next: [Time Scales](Time-Scales)*
|
||||
_Previous: [Crescent Visibility](Crescent-Visibility) | Next: [Time Scales](Time-Scales)_
|
||||
|
|
|
|||
|
|
@ -127,7 +127,10 @@ import { initKernels, getSunMoonEvents } from 'moon-sighting'
|
|||
await initKernels()
|
||||
|
||||
const events = await getSunMoonEvents(new Date('2025-03-29'), {
|
||||
lat: 21.4225, lon: 39.8262, elevation: 300, name: 'Mecca'
|
||||
lat: 21.4225,
|
||||
lon: 39.8262,
|
||||
elevation: 300,
|
||||
name: 'Mecca',
|
||||
})
|
||||
|
||||
console.log(events.sunsetUTC)
|
||||
|
|
@ -202,4 +205,4 @@ npx moon-sighting benchmark
|
|||
|
||||
---
|
||||
|
||||
*Previous: [Home](Home) | Next: [API Reference](API-Reference)*
|
||||
_Previous: [Home](Home) | Next: [API Reference](API-Reference)_
|
||||
|
|
|
|||
|
|
@ -38,7 +38,9 @@ import { initKernels, getMoonSightingReport } from 'moon-sighting'
|
|||
await initKernels()
|
||||
|
||||
const report = await getMoonSightingReport(new Date('2025-03-29'), {
|
||||
lat: 51.5074, lon: -0.1278, elevation: 10
|
||||
lat: 51.5074,
|
||||
lon: -0.1278,
|
||||
elevation: 10,
|
||||
})
|
||||
|
||||
console.log(report.yallop.category) // 'A'
|
||||
|
|
|
|||
|
|
@ -5,6 +5,7 @@
|
|||
The library uses the WGS84 (World Geodetic System 1984) reference ellipsoid, which is the standard for GPS coordinates, Google Maps, and most modern mapping systems.
|
||||
|
||||
Key constants:
|
||||
|
||||
```
|
||||
a = 6378137.0 m (semi-major axis, equatorial radius)
|
||||
1/f = 298.257223563 (inverse flattening)
|
||||
|
|
@ -45,6 +46,7 @@ Up = (cos φ cos λ, cos φ sin λ, sin φ)
|
|||
```
|
||||
|
||||
These are unit vectors. To convert a topocentric ECEF displacement Δ (in meters) to ENU:
|
||||
|
||||
```
|
||||
e = East · Δ
|
||||
n = North · Δ
|
||||
|
|
@ -67,6 +69,7 @@ Altitude is the angle above the horizontal plane: 0° = horizon, 90° = zenith,
|
|||
The Moon's geocentric position (from the ephemeris) differs from its topocentric position (as seen by a surface observer) because the Moon is close enough that the baseline between Earth's center and the observer's surface position is significant. This is the diurnal parallax.
|
||||
|
||||
The correction is simply:
|
||||
|
||||
```
|
||||
topocentric_direction = moon_ITRS − observer_ITRS
|
||||
```
|
||||
|
|
@ -103,6 +106,7 @@ Standard conditions: P = 1013.25 mbar, T = 15°C. The correction factors adjust
|
|||
### Accuracy limits
|
||||
|
||||
The Bennett formula is accurate to:
|
||||
|
||||
- ~0.1 arcminute for h > 5°
|
||||
- ~0.5 arcminute for h = 2°–5°
|
||||
- ~1–2 arcminutes for h < 2°
|
||||
|
|
@ -115,7 +119,7 @@ This is why crescent sighting criteria use "airless" (refraction-free) altitudes
|
|||
### When to apply refraction
|
||||
|
||||
| Use case | Mode |
|
||||
|----------|------|
|
||||
| ------------------------------------ | ------------------- |
|
||||
| Yallop ARCV input | Airless |
|
||||
| Odeh ARCV input | Airless |
|
||||
| Sunset/moonset threshold | Standard refraction |
|
||||
|
|
@ -126,4 +130,4 @@ moon-sighting computes both airless and apparent altitudes for each body positio
|
|||
|
||||
---
|
||||
|
||||
*Previous: [Reference Frames](Reference-Frames) | Next: [Validation](Validation)*
|
||||
_Previous: [Reference Frames](Reference-Frames) | Next: [Validation](Validation)_
|
||||
|
|
|
|||
|
|
@ -13,6 +13,7 @@ The IERS Conventions (2010) define the standard transformation:
|
|||
```
|
||||
|
||||
Where:
|
||||
|
||||
- **GCRS** = Geocentric Celestial Reference System (essentially the inertial J2000 frame at Earth's center)
|
||||
- **ITRS** = International Terrestrial Reference System (Earth-fixed frame, rotates with the solid Earth)
|
||||
- **Q(t)** = celestial motion matrix (precession + nutation)
|
||||
|
|
@ -31,6 +32,7 @@ The IAU 2006 precession model and IAU 2000A nutation model together parameterize
|
|||
- **s:** CIO locator, a small angle that ensures continuity of the CIO position
|
||||
|
||||
The CIP X,Y series has:
|
||||
|
||||
- A polynomial part (degree 5 in T = Julian centuries from J2000.0)
|
||||
- 1,306 luni-solar nutation terms
|
||||
- 687 planetary nutation terms
|
||||
|
|
@ -72,7 +74,7 @@ moon-sighting defaults to xp = yp = 0. Supply current values from IERS Bulletin
|
|||
## IAU 2000A vs 2000B
|
||||
|
||||
| Feature | 2000A | 2000B |
|
||||
|---------|-------|-------|
|
||||
| ---------------- | ------------- | ---------------- |
|
||||
| Luni-solar terms | 1,306 | 77 |
|
||||
| Planetary terms | 687 | 0 |
|
||||
| Max error | < 0.1 mas | < 1 mas |
|
||||
|
|
@ -96,13 +98,15 @@ See [Observer Model](Observer-Model) for the WGS84 and ENU computation details.
|
|||
## Accuracy
|
||||
|
||||
With user-supplied EOP (Earth orientation parameters from IERS Bulletin A):
|
||||
|
||||
- Azimuth/altitude accuracy: < 0.1 arcsecond (dominated by nutation model error)
|
||||
|
||||
With polynomial ΔT approximation (no user EOP):
|
||||
|
||||
- Azimuth/altitude accuracy: typically < 5 arcseconds, occasionally up to ~30 arcseconds in pathological ΔT errors
|
||||
|
||||
For comparison, the Moon's angular diameter is ~1800 arcseconds, and refraction uncertainty near the horizon is 600–900 arcseconds. The frame transform is not the limiting factor for crescent sighting.
|
||||
|
||||
---
|
||||
|
||||
*Previous: [Time Scales](Time-Scales) | Next: [Observer Model](Observer-Model)*
|
||||
_Previous: [Time Scales](Time-Scales) | Next: [Observer Model](Observer-Model)_
|
||||
|
|
|
|||
|
|
@ -106,4 +106,4 @@ The NAIF LSK (`naif0012.tls`) is a plain-text file in NAIF text kernel format. I
|
|||
|
||||
---
|
||||
|
||||
*Previous: [Ephemeris](Ephemeris) | Next: [Reference Frames](Reference-Frames)*
|
||||
_Previous: [Ephemeris](Ephemeris) | Next: [Reference Frames](Reference-Frames)_
|
||||
|
|
|
|||
|
|
@ -21,6 +21,7 @@ NASA NAIF's SPICE toolkit is the authoritative reference for reading JPL ephemer
|
|||
Any deviation in the SPK Chebyshev evaluation from SPICE indicates a parsing or algorithm error in moon-sighting.
|
||||
|
||||
**How to compare:**
|
||||
|
||||
```python
|
||||
import spiceypy as spice
|
||||
spice.furnsh('de442s.bsp')
|
||||
|
|
@ -33,6 +34,7 @@ print(state[:3]) # position in km
|
|||
```
|
||||
|
||||
The moon-sighting equivalent:
|
||||
|
||||
```ts
|
||||
const kernel = SpkKernel.fromFile('de442s.bsp')
|
||||
const ts = computeTimeScales(new Date('2025-03-29T20:00:00Z'))
|
||||
|
|
@ -44,6 +46,7 @@ Expected agreement: < 1 meter (floating-point evaluation precision).
|
|||
### JPL Horizons
|
||||
|
||||
JPL Horizons is the online solar system ephemeris service. It uses the same JPL ephemerides and provides tabular output for:
|
||||
|
||||
- Apparent RA/Dec and az/alt for any observer and time
|
||||
- Observer-centered quantities (elongation, illumination, phase angle)
|
||||
- Rise/transit/set times
|
||||
|
|
@ -52,6 +55,7 @@ Horizons uses SPICE internally, so it represents an independent end-to-end valid
|
|||
|
||||
**How to use for validation:**
|
||||
Go to https://ssd.jpl.nasa.gov/horizons/, select:
|
||||
|
||||
- Target body: Moon (or Sun)
|
||||
- Observer location: user-defined geodetic lat/lon/elevation
|
||||
- Time span: the date of interest
|
||||
|
|
@ -62,7 +66,7 @@ Compare Horizons' output with moon-sighting's topocentric az/alt. Differences of
|
|||
## Acceptance thresholds
|
||||
|
||||
| Quantity | Expected error vs SPICE | Notes |
|
||||
|----------|------------------------|-------|
|
||||
| ---------------------------------- | ----------------------- | ------------------------------------------------------------------- |
|
||||
| Geocentric position | < 1 m (< 0.001 arcsec) | SPK parsing precision |
|
||||
| Topocentric az/alt (with EOP) | < 0.1 arcsec | Frame transform precision |
|
||||
| Topocentric az/alt (polynomial ΔT) | < 30 arcsec | ΔT polynomial error |
|
||||
|
|
@ -98,4 +102,4 @@ Be cautious: ICOP records include weather and observer acuity information that t
|
|||
|
||||
---
|
||||
|
||||
*Previous: [Observer Model](Observer-Model) | Next: [API Reference](API-Reference)*
|
||||
_Previous: [Observer Model](Observer-Model) | Next: [API Reference](API-Reference)_
|
||||
|
|
|
|||
Loading…
Reference in a new issue