Koch

Meaning

Koch houses, like Placidus, divide time, but they follow a single degree: the Midheaven. Some hours before birth, that degree rose in the east and began to climb; at birth, it stands at the top of the sky. Koch cuts this climb into three equal parts of time. The cusps of the 10th, 11th, 12th and 1st houses are the degrees that were rising at four marks. These are the moment the Midheaven degree rose, a third and two thirds of the way through its climb, and the birth itself.

Precisely: the Midheaven degree has a diurnal semi-arc, the time it takes to go from the horizon to the meridian. Step back from the sidereal time of birth by two thirds, then by one third, of that semi-arc. The Ascendant of the birthplace at each of those moments gives the cusps of the 11th and 12th houses. The houses below the horizon are found in the same way, and opposite cusps are 180° apart. The four angles are the cusps of the 1st, 4th, 7th and 10th houses.

The idea is that every house cusp should be an Ascendant of the birthplace, a degree that actually rose there at a moment linked to the birth. That is why it is also called the birthplace system. Koch and Placidus give the same angles and often similar cusps, but they can differ by several degrees, and far from the equator by much more.

Koch has the same weak point as Placidus. Inside the polar circles, some degrees of the zodiac never rise and others never set, and a system built on rising times breaks down: Koch cusps cannot be drawn there. Close to the polar circles, its houses are as lopsided as Placidus’.

In practice

• A common choice in German-speaking countries, where it was born, and used by many astrologers elsewhere who want a time-based system other than Placidus.
• Planets near a cusp may change house between Koch and Placidus; astrologers who use Koch read the 11th and 12th, and the 2nd and 3rd, by its own cusps.
• High latitudes. At 45° north or south, Koch houses range from about 18° to 52° of the zodiac, as Placidus’ do; at 60° they can be under 11° or over 84°.
• Without a reliable birth time the cusps move quickly, as in every quadrant system, and are best read with caution.

Origin and history

The system is named after the German astrologer Walter Koch, who presented it with tables of houses in the 1960s, under the name of birthplace houses. It spread first in German-speaking astrology and then among astrologers elsewhere, and it became one of the standard options of astrological software. Some astrologers object that it builds every cusp from the Midheaven’s semi-arc rather than from each degree’s own, and that it fails, like Placidus, inside the polar circles. Deborah Houlding’s history of the houses (1998) places it among the modern quadrant systems.

How Ulune calculates it

Choose Koch in the birth form’s options. The Swiss Ephemeris computes the cusps with its code K. The Ascendant, the IC, the Descendant and the Midheaven are the cusps of the 1st, 4th, 7th and 10th houses.

Inside the polar circles, beyond about 66°34′ north or south, the Swiss Ephemeris finds no Koch cusps. Ulune then builds that chart’s houses with Porphyry, and a note under the chart says: “Houses in Porphyry: Koch has no cusps inside the polar circles.” Progressed angles and the Vertex follow the same fallback. In a composite chart in Koch, the angles are the midpoint angles and the other cusps keep, inside each quadrant, the average of their places in the two charts.

Correspondences