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145 lines
7.3 KiB
Markdown
145 lines
7.3 KiB
Markdown
# Traditional Methods
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pray-calc supports 14 traditional prayer time methods. They appear in the `Methods`
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field returned by `getTimesAll` and `calcTimesAll`. Each entry is `[fajrTime, ishaTime]`.
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## Method Table
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| ID | Name | Fajr | Isha | Region |
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| --------- | --------------------------------------------- | -------- | -------- | -------------- |
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| `UOIF` | Union des Organisations Islamiques de France | 12° | 12° | France |
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| `ISNACA` | IQNA / Islamic Council of North America | 13° | 13° | Canada |
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| `ISNA` | FCNA / Islamic Society of North America | 15° | 15° | US, UK, AU, NZ |
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| `SAMR` | Spiritual Administration of Muslims of Russia | 16° | 15° | Russia |
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| `IGUT` | Institute of Geophysics, University of Tehran | 17.7° | 14° | Iran, Shia use |
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| `MWL` | Muslim World League | 18° | 17° | Global default |
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| `DIBT` | Diyanet İşleri Başkanlığı, Turkey | 18° | 17° | Turkey |
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| `Karachi` | University of Islamic Sciences, Karachi | 18° | 18° | PK, BD, IN, AF |
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| `Kuwait` | Kuwait Ministry of Islamic Affairs | 18° | 17.5° | Kuwait |
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| `UAQ` | Umm Al-Qura University, Makkah | 18.5° | +90 min | Saudi Arabia |
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| `Qatar` | Qatar / Gulf Standard | 18° | +90 min | Qatar, Gulf |
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| `Egypt` | Egyptian General Authority of Survey | 19.5° | 17.5° | EG, SY, IQ, LB |
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| `MUIS` | Majlis Ugama Islam Singapura | 20° | 18° | Singapore |
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| `MSC` | Moonsighting Committee Worldwide | seasonal | seasonal | Global |
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## Method Notes
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### UOIF (12°/12°)
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The lowest fixed angles in common use, adopted in France. The 12° convention is
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justified by observations showing that at higher European latitudes, the Sun does
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not reach 18° in summer. The French Muslims' Union settled on 12° as a year-round
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compromise that avoids the "nightlessness" problem.
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### ISNACA (13°/13°)
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Used by IQNA (Islamic Quarterly of North America) and some Canadian communities.
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A middle point between UOIF and ISNA, reflecting observations that 15° causes
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very late Isha in Canadian summers.
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### ISNA (15°/15°)
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The Fiqh Council of North America adopted 15° in 2007 after research showing
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18° produced Fajr too early and Isha too late in North American latitudes. This
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was a significant shift from their prior 18°/18° position. Still the most commonly
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used method in the US, UK, Australia, and New Zealand.
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### SAMR (16°/15°)
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The Spiritual Administration of Muslims of Russia uses a split angle: 16° for
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Fajr and 15° for Isha. The asymmetry reflects differing shafaq criteria (red
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twilight fades before white) and the latitudinal challenges of Russian Muslim
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communities, many of whom live above 50°N.
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### IGUT / Tehran (17.7°/14°)
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The Institute of Geophysics at the University of Tehran derived these values from
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observational studies in Iran. The 17.7° Fajr is unusual: close to the historical
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18° but with a slight downward revision. The 14° Isha reflects the Shia tradition
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of using shafaq ahmer (red glow) rather than shafaq abyad (white glow), since red
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twilight disappears earlier. This method is used by Shia communities worldwide and
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in Iran's official calendar.
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### MWL (18°/17°)
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The Muslim World League method is the most widely referenced global default. MWL
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is headquartered in Makkah. The 18°/17° split mirrors the international consensus
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of using 18° for Fajr (astronomical twilight) and allowing Isha slightly earlier
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at 17°. Correct at equatorial and low latitudes; fails at high latitudes in summer.
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### DIBT (18°/17°)
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Diyanet İşleri Başkanlığı is Turkey's official religious authority. The angles are
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identical to MWL, but this is listed as a separate method because the institution
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issues its own official tables and some apps need to distinguish between them for
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attribution purposes.
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### Karachi (18°/18°)
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The University of Islamic Sciences, Karachi uses symmetric 18° for both Fajr and
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Isha. Historically one of the most conservative methods, still used across Pakistan,
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Bangladesh, India, and Afghanistan.
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### Kuwait (18°/17.5°)
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Kuwait's Ministry of Islamic Affairs uses a small Isha relaxation (17.5° instead
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of 18°) relative to Karachi. This method is commonly used across Gulf states that
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do not follow UAQ or Qatar.
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### UAQ (18.5°/+90 min)
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Umm Al-Qura University in Makkah publishes the official Saudi calendar. The Fajr
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angle is 18.5°: more conservative than most methods. Isha uses a fixed 90-minute
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offset from sunset rather than an angle. In Ramadan, UAQ extends this to 120 minutes
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(some implementations; this library uses 90 year-round per the standard).
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The fixed-minute Isha avoids the problem that an angle-based Isha never ends during
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Saudi summer (the Sun stays close to the horizon), while the 90-minute period also
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aligns roughly with the 2 Isha periods (Maghrib + 90 min) used in informal practice.
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### Qatar (18°/+90 min)
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Qatar follows a similar approach to UAQ for Isha: 90 minutes after sunset, year-round.
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Fajr is 18° (not 18.5° as in UAQ). This is the standard in Qatar and some Gulf states
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that have adopted the fixed-minute Isha convention without UAQ's Fajr conservatism.
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### Egypt (19.5°/17.5°)
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The Egyptian General Authority of Survey uses the highest fixed Fajr angle (19.5°)
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of any method. This was historically derived from observations in Egypt's clear desert
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sky, where the faintest pre-dawn light was detected at a relatively deep sun position.
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At the equatorial latitudes where it is used (Egypt, Syria, Iraq, Lebanon), 19.5°
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doesn't cause the extreme errors it would at European latitudes. Isha at 17.5° is
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similar to MWL.
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### MUIS (20°/18°)
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Singapore's Islamic Religious Council uses the most conservative angles in the table.
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Singapore sits at about 1.3°N: very close to the equator: where atmospheric
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conditions and the nearly vertical Sun path do result in a slightly later dawn and
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earlier dusk compared to higher latitudes. The 20° Fajr reflects these local conditions.
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### MSC (Seasonal / Moonsighting Committee Worldwide)
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This is the same underlying algorithm used by the dynamic primary method. Unlike all
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other entries in this table, MSC does not use a fixed angle. The offset is computed
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from the latitude and day-of-year via Khalid Shaukat's piecewise model.
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Including MSC in the comparison table lets you see where the dynamic primary method
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agrees with or diverges from the "raw" MSC output. The dynamic method adds physics
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corrections (r, Fourier, refraction, elevation) on top of the MSC base, so they
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should be close but not identical.
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## Computation
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For all angle-based methods, `getTimesAll` makes a single batch call to the NREL
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Solar Position Algorithm (via `nrel-spa`), passing all 14×2 + 2 dynamic zenith
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angles at once. This is more efficient than 16 separate SPA calls.
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UAQ and Qatar Isha are computed as `sunset + ishaMinutes / 60` after the SPA call.
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MSC Fajr and Isha are computed from the sunrise/sunset times using the minute
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offsets from `getMscFajr` / `getMscIsha`.
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---
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_[Back to Home](Home) | [Dynamic Algorithm](Dynamic-Algorithm) | [API Reference](API-Reference)_
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