Primary Types

•Primary (Zodiacal)

•Primary (In Mundo)

 

Primary Methods

•Placidus (semi-arc) – a point's position is measured as the proportion of its own diurnal or nocturnal semi-arc it has travelled from the meridian. The promissor is directed until it reaches the same proportion of its semi-arc as the significator. Available for both In Mundo and Zodiacal directions. Circumpolar points have no semi-arc and cannot be used as significators.

•Regiomontanus – positions are measured by circles of position, great circles through the north and south points of the horizon (the same circles that form Regiomontanus houses). Each circle has a pole, and the promissor is directed until it lies on the significator's circle, using its oblique ascension under that pole. Available for both In Mundo and Zodiacal directions.

•Placidus (under the pole) – available for Zodiacal primaries only. The older Placidian method found in Placidus's own tables and in Morinus. The significator is given a pole derived from its semi-arc proportion, and the promissor is then directed under that pole in the Regiomontanus manner. Results are close to, but not identical with, the semi-arc method.

 

Primary Keys

•Ptolemy (1°/yr) – one degree of arc equals one year. The traditional key.

•Naibod (59′08″/yr) – one year equals the Sun's mean daily motion in longitude, 0°59′08″ (360° over the length of the year).

•Cardan (59′12″/yr) – Cardan's rounding of the Sun's mean daily motion: one year equals 0°59′12″.

•Kepler (solar RA rate) – one year equals the Sun's actual motion in right ascension on the day of birth, so the rate varies with the birth date (roughly 0°53′ to 1°06″). Also known as the Brahe or birthday-arc key.

•Natal (solar lon rate) – one year equals the Sun's actual motion in ecliptic longitude on the day of birth (roughly 0°57′ to 1°01′).

•Placidus (solar arc in RA) – the true solar arc in right ascension: a direction falls due when the Sun, moving at its real rate on a day-for-a-year basis, has advanced in right ascension by the arc of direction. Rather than a fixed rate, the timing follows the Sun's varying motion through the days after birth, as in secondary progressions. The key recommended by Makransky.

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Latitude Options

•None – both the promissor's aspect point and the significator are taken as zodiacal degrees, without latitude (the traditional degree-to-degree calculation, as in Solar Fire).

•Both – the promissor's aspect point keeps the promissor's full latitude, and the significator is taken as its true body rather than its zodiacal degree.

•Bianchini – as Both, but the aspect point's latitude is reduced according to the aspect (full for a conjunction, about half for sextiles and trines, none for a square, reversed for an opposition), following Bianchini's rule sin(lat) = sin(planet lat) × cos(aspect).

•Promissor – the promissor's aspect point carries the promissor's own latitude; the significator is taken as its zodiacal degree.

•Significator – the promissor's aspect point stays on the ecliptic; the direction is to the significator's true body, latitude included, rather than to its zodiacal degree.

 

Converse/Direct

•Direct – the normal direction: the sky turns as it does after birth, carrying the promissor (From Point) to the significator's place. The promissor is the moved point; the significator keeps its natal position.

•Converse (Classical) – the traditional converse of Ptolemy and Placidus: the roles are exchanged, so the significator is carried to the promissor's place. The arc still follows the real rotation of the sky after birth, but now it is the significator that moves and the promissor that rests. The listing marks the significator as the moved point.

•Converse (Modern) – the converse of most modern authors: promissor and significator keep their roles, but the sky is turned backwards, as if before birth, so the promissor approaches the significator from the other side. Its arc is the same size as the direct arc in the other direction.

 

Points

•Promissor (P1 / From) – the point that is carried by primary motion, chosen under From Points. Its aspect point (the promissor's degree plus the aspect) is what is directed. In the listing it appears in the P1 column, with the position it has been directed to.

•Significator (P2 / To) – the natal point the promissor is directed to, chosen under To Points. It stays fixed in the natal chart and appears in the P2 column with its natal position.

With a Converse (Classical) direction the roles are exchanged in the calculation: the significator is carried back to the promissor, so the P2 column shows the directed position and P1 the natal one. The columns keep the same points either way.