mirror of https://github.com/acamarata/pray-calc-ml.git synced 2026-07-01 03:14:27 +00:00

Aric Camarata 6e0f4a679c Rebuild as Python data science project

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

2026-02-25 19:32:47 -05:00

1.6 KiB

Raw Blame History

Hail, Saudi Arabia — Khalifa 2018

Paper

Khalifa, A.S. "Astronomical determination of Fajr and Isha prayer times at Hail, Saudi Arabia." NRIAG Journal of Astronomy and Geophysics, 7: 22-28, 2018.

Location

Hail (27.52°N, 41.70°E, ~1020m elevation) — a city on the Najd plateau in central Saudi Arabia. The high elevation and desert conditions produce excellent sky transparency.

Method

80 total observation nights in 2014-2015. 32 nights selected for excellent atmospheric visibility (no clouds, no dust). Naked-eye observation by trained observers.

Results

Mean Fajr depression: 14.4° (range 12.8°-16.1°)
Mean Isha depression (Shafaq Abyad): 14.8° (range 13.2°-16.4°)
Seasonal variation: Higher angles in winter, lower in summer (consistent with other studies)

Significance

At 1020m elevation, Hail is the highest-elevation site in the Saudi/Gulf region with published Fajr observations. The results show a slightly higher mean angle than sea-level desert sites in Egypt (13.5°-14.5°), consistent with the hypothesis that elevation increases the apparent depression angle at true dawn (the observer is above more of the atmosphere, so the first light of dawn appears at a slightly steeper angle).

The Hail dataset is particularly useful for the elevation variable in the ML model — it is one of the few high-altitude desert sites with per-season data.

Note for ML Training

The per-season records in verified_sightings.py for Hail are constructed from the paper's reported seasonal means, with observation times estimated from sunrise data. They are marked as "time inferred" in data/raw/sources.md.

1.6 KiB Raw Blame History