← Encyclopedia of Astrology · lesson 82/235
Koch houses
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What it is
Koch is a quadrant house system developed in Germany in the twentieth century and named after the astrologer Walter A. Koch (1895–1970), who published it with tables in the 1960s. Its German name, the Geburtsort-Häusersystem, means the birthplace house system — a name that reflects its claim to be rooted in the horizon of the place of birth.
Like Placidus, it is based on time rather than on dividing a circle in space, and like every quadrant system it makes the four angles the cusps of the angular houses: the Ascendant the 1st, the Imum Coeli the 4th, the Descendant the 7th and the Midheaven the 10th.
How it is worked out
Placidus gives every degree of the zodiac its own measure of time. Koch uses one measure for the whole chart: the time the Midheaven degree itself took to climb from the eastern horizon to the top of the sky.
That span of time is divided into thirds. Koch then asks which degree was rising on the eastern horizon of the birthplace at each of those moments, and those rising degrees become the cusps of the 11th and 12th houses. The same is done below the horizon for the 2nd and 3rd, and the opposite cusps lie across the chart. In effect, each cusp is an Ascendant the birthplace had a little earlier — which is why the system speaks of the birthplace's own horizon.
How it compares
At ordinary latitudes, Koch and Placidus usually give cusps within a few degrees of each other. The differences grow with latitude and matter most for planets near a cusp of the intermediate houses (2nd, 3rd, 5th, 6th, 8th, 9th, 11th and 12th). Houses are of unequal size, and signs can be intercepted — wholly contained within one house.
Koch shares Placidus's weakness at high latitudes: above roughly 66°, where some degrees of the zodiac never rise, the time it needs cannot be found, and the system fails. Well before that, the houses become very uneven.
In the tradition
Koch belongs to the German astrology of the mid-twentieth century, with its enthusiasm for geometry and great circles, and it grew out of calculations by other researchers before Koch gave it his name. It spread widely in German-speaking countries and enjoyed a period of popularity in the United States in the 1970s and 1980s. Its critics argued from the start that it borrows Ascendants from moments that are not the birth moment and joins them into one chart; its defenders reply that every quadrant system is a way of reading the birthplace's sky through time, and this one simply makes that explicit. Brady's point about house systems applies: there is no right or wrong one, only different grids.
In a reading here
Koch is one of the seven house systems Viastaro offers. Charts use Placidus unless another system is chosen, as a default for the account and per person in the reading settings.