mirror of
https://github.com/acamarata/pray-calc-ml.git
synced 2026-07-02 20:00:40 +00:00
6e0f4a679c
Replaces the original JS calibration library with a pure Python pipeline for collecting and back-calculating solar depression angles from human-verified Fajr and Isha prayer sightings. What this does: - src/pipeline.py: master pipeline; fetches iCal + manual records, back-calculates angles via PyEphem, applies quality filters, exports two clean CSVs - src/collect/openfajr.py: parses the OpenFajr Birmingham iCal feed (~4,018 records) - src/collect/verified_sightings.py: manually compiled records from peer-reviewed studies (Egypt, Saudi Arabia, Malaysia, Indonesia, UK, USA, Canada, and more) - src/angle_calc.py: PyEphem back-calculation with atmospheric refraction - src/elevation.py: Open-Elevation API batch lookup Datasets generated: - data/processed/fajr_angles.csv: 4,105 confirmed Fajr records, 35 locations, latitude range -37.8 to 53.7 degrees, date range 1985-2026 - data/processed/isha_angles.csv: 43 confirmed Isha records, 20+ locations Also includes: - notebooks/01_exploratory_analysis.ipynb: latitude, TOY, elevation pattern analysis - research/: academic paper summaries (not training data) - data/raw/sources.md: full citation table for all data sources
59 lines
2.8 KiB
Markdown
59 lines
2.8 KiB
Markdown
# NRIAG Egypt Studies: 1984-2014
|
|
|
|
## Summary
|
|
|
|
The National Research Institute of Astronomy and Geophysics (NRIAG, Egypt) conducted the
|
|
most extensive body of peer-reviewed naked-eye Fajr observations anywhere in the world.
|
|
Multiple campaigns from 1984 to 2014 covered six Egyptian sites across a wide range of
|
|
latitudes, elevations, and atmospheric conditions.
|
|
|
|
## Key Paper
|
|
|
|
Hassan, A.H., et al. "Astronomical determination of the proper time for Fajr prayer."
|
|
*NRIAG Journal of Astronomy and Geophysics*, 3(1): 23-26, 2014.
|
|
DOI: S2090997714000054
|
|
|
|
## Sites and Findings
|
|
|
|
| Site | Lat/Lng | Elevation | Years | Mean Fajr Angle | Conditions |
|
|
| --- | --- | --- | --- | --- | --- |
|
|
| Kottamia Observatory | 30.03°N, 31.83°E | 477m | 1984-1987 | 13.5° | Elevated desert observatory; photoelectric + naked eye |
|
|
| Helwan | 29.86°N, 31.34°E | 114m | 1984-1987 | 13.1° | Peri-urban; slight light pollution |
|
|
| Aswan | 24.09°N, 32.90°E | 92m | 1984-1987 | 14.0° | Near-equatorial desert; clearest conditions |
|
|
| Siwa Oasis | 29.20°N, 25.52°E | -18m | 2005-2007 | 14.8° | Below sea level; very dry; exceptional clarity |
|
|
| Mersa Matrouh | 31.36°N, 27.24°E | 26m | 2005-2007 | 13.7° | Mediterranean coast |
|
|
| Assiut | 27.17°N, 31.17°E | 55m | 2010-2013 | 13.7° | Nile Valley; agricultural; slightly lower than desert |
|
|
|
|
## Second NRIAG Paper
|
|
|
|
Hassan, A.H., et al. "Determination of Fajr twilight at five Egyptian sites."
|
|
*NRIAG Journal of Astronomy and Geophysics*, 5: 9-15, 2016.
|
|
|
|
Sites: Sinai (31.07°N, 30m), Assiut (27.17°N, 55m), Kharga Oasis (25.45°N, 74m), Qena
|
|
(26.16°N, 96m), and others. Results consistent with earlier campaign: 13°-15°.
|
|
|
|
Sinai desert specifically: 14.84° mean angle (n=47 nights).
|
|
Nile Valley sites: systematically lower by ~1° (agricultural aerosols reducing sky clarity).
|
|
|
|
## Isha Findings
|
|
|
|
The same papers cover Isha (Shafaq al-Abyad, white dusk twilight):
|
|
- Mean Isha angles: 14.3°-15.8° across Egyptian sites
|
|
- Shafaq al-Ahmar (red dusk) disappears earlier: ~10°-12°
|
|
|
|
## Key Conclusions
|
|
|
|
1. The 18° convention overstates true dawn by a significant margin. At most Egyptian sites, the
|
|
sky begins to lighten at 13°-15° depression.
|
|
2. Desert sites consistently yield slightly higher angles than agricultural or coastal sites,
|
|
likely due to atmospheric aerosol differences.
|
|
3. Results are consistent across a 30-year span (1984-2014) and multiple independent teams.
|
|
4. No systematic seasonal trend is reported — but Egypt spans only 22°-31°N, limiting latitude
|
|
range for seasonal analysis.
|
|
|
|
## Data Note
|
|
|
|
These papers report mean angles and statistical distributions, not per-date timestamps with
|
|
explicit times. The per-date ML training records for Egypt in this project are derived from
|
|
the published means using estimated observation times, and are marked accordingly in
|
|
`data/raw/sources.md`.
|