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62 lines
1.7 KiB
Markdown
62 lines
1.7 KiB
Markdown
[**moon-sighting v1.1.1**](../README.md)
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***
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[moon-sighting](../README.md) / getMoonVisibilityEstimate
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# Function: getMoonVisibilityEstimate()
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> **getMoonVisibilityEstimate**(`date?`, `lat`, `lon`, `elevation?`): [`MoonVisibilityEstimate`](../interfaces/MoonVisibilityEstimate.md)
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Defined in: [api/index.ts:647](https://github.com/acamarata/moon-sighting/blob/2992dcee216cb24cc74542f6e8d5a6f4f0d16e05/src/api/index.ts#L647)
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Quick kernel-free crescent visibility estimate using the Odeh criterion.
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Computes approximate crescent geometry (ARCL, ARCV, W) from Meeus Ch. 47
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positions at the given observation time and applies the Odeh V-parameter formula.
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Accuracy is limited by the Meeus approximation (~0.3°) and the fact that
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"best time" is not computed — pass your estimated observation time.
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For precise crescent work, use getMoonSightingReport() with the DE442S kernel.
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## Parameters
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### date?
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`Date` = `...`
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Observation time (default: now). Use a post-sunset time for best results.
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### lat
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`number`
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Observer geodetic latitude in degrees (north positive)
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### lon
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`number`
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Observer longitude in degrees (east positive)
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### elevation?
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`number` = `0`
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Observer height above WGS84 ellipsoid in meters (default: 0)
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## Returns
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[`MoonVisibilityEstimate`](../interfaces/MoonVisibilityEstimate.md)
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MoonVisibilityEstimate with Odeh V, zone, and geometry values
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## Example
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```ts
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// Estimate crescent visibility at sunset + 40 min in Mecca
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const obs = new Date('2025-03-01T15:30:00Z') // ~sunset + 40 min in Mecca
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const est = getMoonVisibilityEstimate(obs, 21.42, 39.83)
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console.log(est.zone) // 'A' through 'D'
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console.log(est.isVisibleNakedEye) // true/false
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```
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