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
1.8 KiB
Research Archive
This folder contains summaries of academic and institutional research on Islamic twilight
angles. These papers describe other researchers' conclusions about the solar depression angle
at Fajr and Isha. They are useful for understanding the scientific landscape but are not
used as ML training data — only raw per-date observations with explicit timestamps feed
the data/processed/ datasets.
Summary: What the research says
Most peer-reviewed naked-eye studies find Fajr (true dawn / Subh Sadiq) corresponds to a solar depression of roughly 13°–16° depending on site, season, and atmospheric conditions. Isha (Shafaq al-Abyad, white dusk twilight) corresponds to roughly 14°–18°.
The classic convention of 18° Fajr (used by ISNA, MWL, and others) is based on astronomical twilight (the sky becoming fully dark), not the first appearance of dawn light. Observations consistently show true dawn appears while the sun is 12°–15° below the horizon, not 18°.
Papers Summarized
| File | Authors | Year | Site | Finding |
|---|---|---|---|---|
nriag-egypt-1984-2014.md |
Hassan et al. | 1984-2014 | Egypt (6 sites) | 13°-15° Fajr |
nriag-egypt-2022-2025.md |
Rashed et al. | 2018-2025 | Egypt (Fayum, Alex) | 13°-14° Fajr |
hail-saudi-2018.md |
Khalifa | 2014-2015 | Hail, Saudi Arabia | 14° mean Fajr |
malaysia-indonesia-2018.md |
Kassim Bahali | 2017 | KL + Indonesia | 16.67° Fajr |
depok-indonesia-2020.md |
Saksono | 2015 | Depok, Java | ~16° Fajr |
uk-observations.md |
Yusuf, Hizbul Ulama | 1987-2017 | UK (3 sites) | 12°-14° Fajr |
birmingham-openfajr.md |
OpenFajr project | 2016-2026 | Birmingham | 12.5°-14° Fajr |
moonsighting-global.md |
Khalid Shaukat | 2000s | Multiple global | 15°-18° Fajr |