Shaum

A production-grade Rust library for Islamic fasting (Shaum) jurisprudence with high-precision astronomical calculations for Hilal visibility.

Features

Fiqh Engine

• Hijri Conversion: Umm al-Qura algorithm with moon-sighting adjustment support.
• Rule Priority: Haram > Wajib > Sunnah > Makruh > Mubah.
• Status Classification:
  • Wajib: Ramadan
  • Haram: Eid al-Fitr, Eid al-Adha, Days of Tashriq
  • Sunnah: Arafah, Ashura, Tasu'a, Ayyamul Bidh, Mondays, Thursdays, Shawwal
  • Makruh: Singling out Friday or Saturday

Astronomy Engine (v0.5.0)

Native high-precision ephemeris calculations for Hilal visibility determination:

• Sun Position: VSOP87 theory (~1 arcsec precision)
• Moon Position: ELP2000-82 theory (~1 arcsec precision)
• Coordinate Systems: Ecliptic, Equatorial, Horizontal
• Corrections: Topocentric parallax, atmospheric refraction (Bennett)
• Visibility: MABIMS criteria (altitude ≥ 3°, elongation ≥ 6.4°)

Validated against 87 years of historical Indonesian Ramadan dates (1938-2024).

Usage

[dependencies]

shaum = "0.5"

Fasting Status

use shaum::prelude::*;
use chrono::NaiveDate;

let date = NaiveDate::from_ymd_opt(2025, 6, 5).unwrap();
let analysis = shaum::analyze_date(date);

println!("Status: {:?}", analysis.primary_status);

Hilal Visibility

use shaum::astronomy::visibility::calculate_visibility;
use shaum::types::GeoCoordinate;
use chrono::{Utc, TimeZone};

let jakarta = GeoCoordinate { lat: -6.2088, lng: 106.8456 };
let sunset = Utc.with_ymd_and_hms(2026, 2, 17, 11, 0, 0).unwrap();

let report = calculate_visibility(sunset, jakarta);

println!("Altitude: {:.2}°", report.moon_altitude);
println!("Elongation: {:.2}°", report.elongation);
println!("MABIMS: {}", report.meets_mabims);

Validation

References

• Jean Meeus, Astronomical Algorithms (2nd ed.)
• MABIMS visibility criteria (Indonesia/Malaysia/Brunei/Singapore)
• VSOP87 (Bretagnon & Francou, 1988)
• ELP2000-82 (Chapront-Touzé & Chapront, 1983)

License

MIT License. Copyright (c) 2026 Mohammad Farid Hendianto.