Malaysia Hilal Astronomy Simulator: MABIMS Visibility & Optical Simulation
Malaysia Hilal Simulator
Scientific Study of Lunar Crescent Visualisation Based on Equatorial Astronomical Parameters.
Falak Configuration Hub
Interactive Sky Viewer
Calculated Results & Official Verdict
Visibility Constraint
Ready for calculation.
Technical Analysis
Enter a date to see the scientific breakdown.
Recommended Action
Guidelines for Rukyah teams.
Visual Metric Analysis
Knowledge Base: Islamic Astronomy (Falak)
Sighting a Hilal is not merely about its existence, but its Contrast Ratio against the twilight sky. At sunset, the sky brightness is at its peak. As the Sun sinks further (between 6 to 12 degrees altitude), the sky darkens exponentially, but the Moon also approaches the horizon. The Golden Window for sighting occurs when the sky is dark enough to reveal the crescent, but before the Moon sets into the thickest atmospheric extinction layer.
Section 2: Atmospheric Refraction ParadoxDue to the density of Earth's atmosphere, light rays are bent. This means when we see the Moon sitting exactly on the horizon, it has technically already set geometrically by about 34 arcminutes (roughly 0.5 degrees). In Falak calculations, this Apparent Altitude must be carefully distinguished from Geometric Altitude to avoid false positive predictions during official Rukyah.
Section 3: Equatorial Geometry and the Moon BoatMalaysia's proximity to the Equator results in a unique visual orientation. In northern or southern latitudes, the Hilal often appears tilted or standing sideways. Near the Equator, the ecliptic path is nearly vertical. Consequently, the Hilal often appears like a Moon Boat where the cusps point upward, which provides the maximum possible altitude for any given elongation, optimizing sighting conditions compared to Europe or Australia.
Section 4: The Danjon Limit and Cusp TruncationFrench astronomer Andre-Louis Danjon discovered that when the Moon is within approximately 7 degrees of the Sun, the crescent horns or cusps effectively vanish. This happens because the shadows cast by mountains on the lunar surface at such grazing angles are longer than the illuminated portions. The MABIMS 6.4 degree elongation criterion is a modern refinement of this physical limit, ensuring the crescent is physically continuous enough to be seen.
Section 5: Modern Imkanur Rukyah FrameworkThe MABIMS 2021 criteria (3 degrees Altitude and 6.4 degrees Elongation) are derived from the Odeh Criterion, which analyzed over 700 historical sighting reports. It represents a shift from purely geometric calculations to a probability-based model that accounts for human visual thresholds and typical equatorial weather patterns found in the Southeast Asian region.
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