Thanks for the tip Nonsonoqui. Download takes a little while but it’s a full-blown astrological software with many many features: http://www.starfisher.cz/starfisher/EN/features.htm
This is a calculator created for determining astrological midpoints. It will calculate the “near” and “far” midpoints between 2 locations in a chart since any two points in a 360 degree chart will have 2 midpoints, both of them exactly 180 degrees in opposition. In most cases you will want to use the “near” midpoint in your astrological calculations.
Midpoints are one of the most powerful tools in astrology but are often ignored because they are difficult to calculate. Used correctly, they allow you to find the synthesis of two points or planets in an astrological chart and can provide very powerful methods of interpretation. For example, a Composite chart between two individuals consists of the midpoints of both person’s charts cast into a third chart. In recent years, midpoint astrology has seen a resurgence and is particularly popular in England. If you’d like to find out more about midpoint astrology, there are some good links at the bottom of this page.