2 articles for "Koch House System"

**Koch House System**[Astro*Index]

Also called the *Birthplace House System*. Tables for this system first appeared in 1971, in an English translation of the work of Walter Koch. In spite of the claims of priority and originality made for this method, it is but a simple modification of the *Alcabitus System*. For cusps above the *Horizon*, the *semidiurnal arc* (along a *small circle*) of the *Rising Degree* (Ascendant) is trisected; then, altitude circles (*small circle*s parallel to the Horizon) are constructed through the points of trisection; finally, the cusps are determined by the intersections of these altitude circles with the *Ecliptic*. For cusps below the Horizon, the seminocturnal arc is used. The MC and ASC, are the same, respectively, as the cusps of the 10^{th} and 1^{st} houses.

sin(Z) = sin(ST)tan(LAT)tan(obl) For n=1,2,3,...12: Bn = (60°+30°n) mod 360° Gn = Bn/90-1, and Kn = +1, for 0° <= Bn < 180° Gn = Bn/90-3, and Kn = -1, for 180° <= Bn < 360° Hn = ST + Bn + GnZ Xn = cos(Hn)cos(obl) - Kntan(LAT)sin(obl) Yn = sin(Hn) Ln = atan2(Yn,Xn) Example: Given that: obl = +23.45° LAT = +37.00° ST = 07:32:00 = 113.00° Then, Z = +17.510957° B10 = 0°, G10 = +1, H10 = 130.5110° B11 = 30°, G11 = +1, H11 = 160.5110° B12 = 60°, G12 = +1, H12 = 190.5110° B1 = 90°, G1 = +1, H1 = 220.5110° B2 = 120°, G2 = +1, H2 = 250.5110° B3 = 150°, G3 = +1, H3 = 280.5110° For n=11 (11th cusp): X11 = -0.564969 Y11 = +0.333626 L11 = 166.9742° For completeness: MC = 10: 11: 166.9742° = 12: 1: 2: 3:

See also:

♦ House Cusp ♦ House System ♦ Placidus House System ♦ Alcabitus System ♦ Horizon ♦ Small Circle ♦ Rising ♦ Ecliptic

**Koch House System**[Prima]

One of several house systems.

The Koch house system, also known as the Birthplace system, is a time-based system that is similar to the Placidus house system. Tables for this system first appeared in 1971 in an English translation of the work of Walter Koch.

In this system the house cusps are calculated through the division of arcs and their projection onto the ecliptic as follows:

**- For cusps above the horizon:**

the semi-nocturnal arc (along a small circle) of the rising degree (ascendant) is trisected; then, altitude circles (small circles parallel to the horizon) are constructed through the points of trisection; finally, the cusps are determined by the intersections of these altitude circles with the ecliptic.

**- For cusps below the horizon:**

the semi-nocturnal arc is used. The MC and ascendant are the same respectively, as the cusps of the 10^{th} and 1^{st} houses. This system is ill-defined at extreme latitudes.

See also:

♦ House Cusp ♦ House System ♦ Placidus House System ♦ Alcabitus System ♦ Horizon ♦ Small Circle ♦ Rising ♦ Ecliptic

Astro*Index Copyright © 1997 Michael Erlewine