Friday, May 19, 2006

Composite A*C*G Map

Matrix's new program called "Horizons" is able to calculate a composite A*C*G map. As it is the first astrology program that can calculate and draw this type of map I was very interested to find out if it is a new technique that can be used in synastry.

When I examined a composite A*C*G map something didn't look right about it, so I decided to take a closer look at this to try and find out why. It wasn't long before I realised that the composite A*C*G map was calculated according to which chart was entered first in the program. This means that there are two different composite A*C*G maps!!

To make this clearer I will use the composite A*C*G map for O.J. Simpson and Nicole Brown.

When O.J.'s chart is entered first, JU IC is close to Los Angeles, with PL ASC within orb. When Nicole's chart is entered first, there are no planetary lines within orb of Los Angeles.

1). O.J. & Nicole

2). Nicole & O.J.

I do not understand why Horizons calculates TWO composite A*C*G maps for ONE composite chart.

An A*C*G map cannot be drawn from a composite chart as it is calculated using midpoints. The only way to achieve this is by calculating the midpoints between planetary lines on two individual A*C*G maps. The midpoint between the two SU MH lines gives the composite SU MH line. This is repeated for the other 39 planetary lines.

O.J. SU MH line = 60 W 45, Nicole SU MH line = 164 E 07.
The midpoint between these two lines is 51 E 41.
60 45 + 164 07 = 224 52 / 2 = 112 26
164 E 07 - 112 26 = 51 E 41

O.J. MO MH line = 170 W 56, Nicole MO MH line = 60 W 30.
The midpoint between these lines is 115 W 43.
170 56 - 60 30 = 110 26 / 2 = 55 13
60 W 30 + 55 13 = 115 W 43

This is repeated for the other MH and IC lines.

The calculation for the composite ASC and DSC lines is more complex because declination needs to be taken into consideration. Especially when the two charts have a planet with north and south declination, i.e. person A has SU ASC north declination and person B has SU ASC south declination.

Although the calculations for a composite A*C*G map are very difficult, especially the ASC and DSC lines, it shouldn't be a big problem as computer technology is much more advanced than it was many years ago.

I recommend that the Horizons composite A*C*G map not be used as it gives the wrong information. For years I've been using the relationship/Davison A*C*G map as it is based on a real date, time and place of birth.


Blogger Pemo said...

Kepler astrological software has been producing ACG maps of composite charts for at least 5 and perhaps more than 10 years, and Kepler uses the assumption that the composite declination, latitude, and right ascension of the planets is also the midpoints in these coordinates. It appears to me that the ZET program and Kepler use similar assumptions, and you may be incorrect when you say that these are the only programs that produce astromaps of composite charts. For further clarification you can contact David Cochrane of Kepler software at

6:17 pm  

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