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☽ Hilal Tracker

About Hilal Tracker

An astronomical prediction tool for Eid al-Fitr timing, following the crescent moon-sighting principles of the Council of Shia Muslim Scholars of North America and the guidelines of Ayatollah Sistani.

Principles of Crescent Moon-Sighting

“The crescent moon-sighting is only confirmed through the ability to see it with the naked eye.”

Naked-Eye Requirement

Jurists reject depending solely on astronomical calculations. The Quranic reference to “crescents” (not “moon”) denotes a specific phase requiring naked-eye visibility accessible to the general population. Using telescopes contradicts this inclusive address to all people, not specialized groups. Technology can detect the moon during phases invisible to normal vision, making it inappropriate as a primary method.

Acceptance of Astronomical Data

Jurists accept astronomical predictions stating sighting is impossible (e.g., moon below horizon at sunset). They also accept predictions indicating sighting is possible under clear conditions, if the opinion provides reasonable comfort. This is exactly what Hilal Tracker provides.

Horizons

Ayatollah Sistani follows the multiplicity of horizons doctrine: each area has its own horizon. Sighting confirmation requires similar crescent altitude and size between locations. This is distinct from the “unity of horizons” view (per Grand Ayatollah al-Khoei) where sighting in one area applies to all lands sharing that night.

Testimony Requirements

  • Two just (adil) witnesses — not merely reliable individuals, but persons of verified moral standing
  • Testimony must come from areas where sighting is astronomically possible
  • Weather conditions must make sighting reasonably probable
  • Single-person claims cannot bind the community
  • If equally qualified observers under clear skies do not see the crescent, the testimony of two who claim otherwise is not accepted

Source: Council of Shia Muslim Scholars of North America — Principles of Crescent Moon-Sighting

Frequently Asked Questions

From the Moon-Sighting Committee of the Council of Shia Muslim Scholars of North America, operating continuously since 2007.

Why are announcements sometimes released before sunset on West Coast cities?

Two factors justify this: First, when reliable astronomical calculations confirm there is no possibility of sighting the crescent in those areas, immediate announcement is appropriate. Second, the horizon unity principle means crescent sighting in one area applies to all areas of the same horizon sharing identical crescent altitude and light conditions, identifiable hours before sunset.

Why doesn’t the committee accept some local crescent sighting testimonies?

Acceptance requires strict jurisprudential criteria: testimony from areas where sighting is astronomically possible, reasonable probability according to weather forecasts, two just (adil) witnesses specifically, testimony consistent with prevailing reports from that area, and recognition that single-person claims cannot bind the community.

Does the committee cooperate with non-Council members?

The committee accepts crescent sighting from anyone when it meets religious standards and provides accurate and useful data that engenders certainty or contentment, regardless of Council membership status.

Is there objection to multiple regional moon-sighting committees?

There is no need for multiple committees if current members remain qualified, but no one has absolute power to prevent others from establishing committees. Multiple committees are acceptable if operating according to religious criteria, though this could create unnecessary division and confusion among believers.

Our Methodology

Hilal Tracker uses the Odeh visibility criterion (2006) to predict whether the new crescent moon can be seen with the naked eye from your location. This criterion is based on 737 real-world observations and uses the moon’s altitude, crescent width, and elongation from the sun to calculate a visibility score (q-value).

Astronomical calculations are performed using Skyfield, a high-precision Python astronomy library backed by NASA JPL ephemeris data (DE421). Moon and sun positions are computed topocentrically — accounting for your exact location on Earth, not just a generic estimate.

Ramadan start dates are computed using the same sighting-based methodology, not the Umm al-Qura (Saudi) calendar. This ensures the 29th of Ramadan aligns with the actual determination used by Shia communities following Sistani.

The shared-horizon scan checks cities within your latitude band to the west, where later sunsets mean the moon is older and more visible, to determine if a sighting elsewhere could apply to your location per Sistani’s horizon doctrine.

Important Disclaimer

This is an astronomical prediction tool, not a religious ruling. It predicts whether the crescent could theoretically be visible under clear sky conditions. Actual visibility depends on weather, atmospheric clarity, light pollution, and the observer’s eyesight.

The determination of Eid al-Fitr requires confirmed sighting by qualified witnesses per your marja’s guidelines. Always follow the ruling of your local Islamic authority and the Moon-Sighting Committee.

Sources & Citations