Regiomontanus

Definition

Regiomontanus is a quadrant house system named after the fifteenth-century mathematician and astronomer Johannes Müller von Königsberg, who was known by the Latin name Regiomontanus. The method divides the celestial equator into twelve equal sections and projects those divisions onto the ecliptic using great circles drawn through the north and south points of the horizon. The Ascendant and Midheaven remain important reference points, while intermediate house cusps vary according to time and location.

Astrological Meaning

In chart interpretation, Regiomontanus determines which houses contain planets and where the intermediate cusps fall. Because houses describe areas of experience, changing from another system to Regiomontanus can shift a planet into a neighboring house and alter its contextual emphasis without changing its sign, degree, or aspects. The system became especially influential in traditional horary astrology and is closely associated with the methods later popularized by William Lilly.

Why It Matters

Regiomontanus matters because the chosen house system can shape practical chart judgment, particularly when a planet lies near a cusp. Astrologers may select it for historical consistency, horary technique, or personal practice. At extreme latitudes, its cusps can become highly unequal or difficult to calculate, so comparison with other systems may be useful. A sound interpretation states which house system is being used and treats house placement as one factor among planetary condition, rulership, aspects, and chart context.

Related Encyclopedia Entries

• Traditional Astrology
• Astrological Terminology
• Natal Chart
• House Systems
• Horary Astrology
• William Lilly