Alcabitius

How it divides the sky

Alcabitius uses diurnal and nocturnal arcs. The arc from Ascendant to MC, or MC to Ascendant (depending on direction), is divided into 3 equal time arcs. Quadrant-based but different from Placidus. Generally yields very similar results to Placidus.

When to use it

The default if you work with medieval Arab astrology literature. Was the bridge from the Hellenistic period to modern West. Rare in modern practice.

History

Al-Qabisi wrote in 10th-century Baghdad; was translated to Latin and used in Europe until the 16th century.