Composite Chart Houses

This option applies only to the calculation of "Composite – Midpoints" charts. In most cases the calculation of these charts is straightforward, and the house cusps of the chart are simply the midpoints of the same house cusps in the two base charts. However, if the house cusps of the two base charts are almost diametrically opposed, then it is possible that a chart made up of the short-arc midpoints of the base chart’s house cusps will have its cusps out of zodiacal order. When this happens, Solar Fire will adjust some of the house cusps to be long-arc midpoints instead of short-arc in order to preserve the correct zodiacal ordering of the houses. In the "Preferences" dialog, "Houses" tab you can specify any of the three following ways that this adjustment is to be made...

•Auto Anchor – The 1st and 10th house cusps of the base charts are tested to see which one has the “strongest” composite midpoint, and then that cusp is taken as a short-arc midpoint, and other house cusps adjusted as required to maintain correct zodiacal order of the cusps. The “strongest” midpoint is the one in which the short-arc difference in angle between the cusps on the two base charts is a minimum.

•Anchor on 1st House – The 1st house cusp is always taken as the short-arc midpoint, and other house cusps adjusted as required to maintain correct zodiacal order of the cusps.

•Anchor on 10th House - The 10th house cusp is always taken as the short-arc midpoint, and other house cusps adjusted as required to maintain correct zodiacal order of the cusps.