← Sakan · سَكَن
المرصد
al-Marṣad · Hilal Network

Open, research-grade crescent-moon science: the ummah's eyes on the sky, with sensor-attested physics — positive and negative sightings. Documentation, never a verdict.

This network documents observations; it does not declare months. The start of Hijri months is established by the testimony of witnesses accepted by your local religious authority. Reports here — including many honest eyes searching and not seeing — are observational data offered to the community, to hilāl committees, and to researchers. Where this map and an official calendar disagree, the difference is presented as information, never as a verdict.

Live month

Aggregate figures for the selected lunar month. Declared and undeclared reports are separated everywhere.

Reports over the Odeh visibility envelope

Each report placed by its arc of vision (ARCV) and topocentric crescent width (W), over the Yallop 1997 / Odeh 2004 criterion curves. Watching the crowd trace the criterion in real time is this page's signature.

seen · naked eye seen · optical aid not seen flagged (P0/P1)

World map — tonight's search

Every report as a coarse geohash-5 pin (±2.4 km; exact coordinates never leave the device). Filled = declared, outline = undeclared. The terminator sweeps west as the ummah searches.

seen not seen undeclared (outline) filled = declared

Official calendars & their criteria

The network never adjudicates between authorities; it records what the sky showed. Each body applies its own stated criterion. Automated official-calendar feeds are a planned integration (RP3).

AuthorityStated criterion (summary)
Umm al-Qurā (Saudi)moon sets after sun at Makkah & born before sunset — an astronomical, not sighting, rule
MABIMS (2021)elongation ≥ 6.4° AND moon altitude ≥ 3°
Turkey (Diyanet)altitude ≥ 5° AND elongation ≥ 8° (post-2016 int'l criterion)
Morocco (Ḥabous)actual naked-eye sighting reported to the authority
Moonsighting.comglobal visibility curve (Odeh/Yallop), actual reports collated

Where an authority publishes a month-start and the network's first corroborated (P3+/P4) sighting differ, the offset is shown as information, never a verdict.

Open data

Monthly frozen snapshots under CC-BY 4.0. Public schema only: rounded time, geohash-5, result, method, witness class, plausibility + physics components. No photos, no keys, no gate artifacts.

Open dataset
CC-BY 4.0 · DOI reserved on first frozen release (Zenodo)
↓ CSV

Cite as: Hilal Network / Sakan — al-Marṣad open moonsighting dataset (YEAR), sakan.athanapp.site

Research program

A sensor-attested corpus with systematic negative reports and per-witness cryptographic consistency is novel — no existing hilāl corpus has it. Designed to grow with the data.

RP1Recalibrating the Yallop/Odeh visibility criteria on sensor-attested data — negatives finally give a true false-positive axis.
RP2Light pollution & atmosphere vs first visibility (VIIRS radiance join).
RP3Official-calendar drift atlas — offsets per authority per month.
RP4Optical-aid stratification & a crowd-tested Danjon limit.
RP5Crowd reliability — Bayesian truth-discovery over pseudonym keys.
RP6Testimony authentication (privacy-bound, vault-only).
RP7Fiqh–astronomy interface — a neutral evidence base for the ru'yah vs ḥisāb discourse.

Methodology — scrutiny is a feature

Every plausibility score comes from published formulas, computed server-side and independently of the client's own numbers (an observer cannot inflate their own score). The relay uses skyfield + JPL DE421.

// Yallop 1997 (NAO Technical Note 69) — q, ARCV geocentric, W′ topocentric arcmin q = (ARCV − (11.83716.3226·W′ + 0.7319·W′² − 0.1018·W′³)) / 10 // zones: A q>+0.216 · B >−0.014 · C >−0.160 · D >−0.232 · E >−0.293 · F below // Odeh 2004 (Experimental Astronomy 18:39) — V, ARCV airless topocentric, W topocentric arcmin V = ARCV − (7.16516.3226·W + 0.7319·W² − 0.1018·W³) // zones: A V≥5.65 (naked eye) · B ≥2 · C ≥−0.96 (optical aid) · D not visible // evaluated at best time Tb = sunset + (4/9)·(moonset − sunset) · Danjon limit ARCL 6.4°