Elva_Howson wrote:Hello Robert and other members. ... As Lunar Returns vary in time interval from month to month then surely we should be basing our calculations of Minor Progressions on this 'True Rate' not a 'Mean Rate' of motion.
The same can be said for Tertiary Progressions although one Australian software supplier now (after much badgering from me some years ago) offers a True Rate option as well as a Mean Rate option for Tertiaries.
Thank you for your post. I am relieved to find that at least one other professional astrologer on the planet uses Minor Progressions!
The Io Edition astrology software for the Macintosh has always used the True Moon for its Minor Progression calculations. Solar Fire uses the Mean Moon and this can result in a difference of about two hours in the derived ephemeris date and time. Thanks to you, Solar Fire now has a True Tertiary option.
I had asked Graham Dawson for several years in the 1990s to make visible the derived ephemeris date and time for the program's secondary, tertiary and minor progressed calculations so that one could look to see if progressed stations were occurring. This feature was added to Solar Fire v5 and can be found in the "Report" option for any progressed chartwheel.
The progression of the angles in the tertiaries and minors is tricky business as the various software companies all have different calculation options. The Io Edition, for example, uses solar arc in longitude to calculate the minor progressed MC and then computes the minor progressed ASC for either the natal latitude or the relocated latitude. For the tertiary progressed angles, the Io Edition offers either a Quotidian or a solar arc in longitude option for obtaining the TP MC.
I don't know if you have my Volume I - Progressions, but the many methods for progressing the angles were discussed in that book.