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Student of Astrology
 
Join Date: 20 Apr 2002
Location: Wigan, UK
Posts: 7,888
Minderwiz 
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Quote:
Originally Posted by Barleywine View Post
That one is on my list. I'm currently reading Charles Jayne's "Progressions and Directions" published in rather "home-made" fashion by his Astrological Bureau back in the '70s. Since I have Riyal set up for sidereal, I can very easily produce sidereal natal charts to use with Gansten's method. I really need to read Fagan and Firebrace's "Primer of Sidereal Astrology" before I venture into that territory, though.
There's no need to mug up on sidereal approaches for Gansten's book. It only becomes an issue if you try to follow his worked example (using a calculator or a spreadsheet). This is not necessary for understanding the principles, as he confines the calculation to an appendix. However being something of a masochist, I decided to try and work through the calculations to test my understanding.

The problem comes when he uses an example from earlier in the book. In the example Mercury is quoted at 15, 17 Cancer but in the example of the detailed calculation Mercury's longitude is quoted as 128 degrees 25 minutes. Now 15, 17 Cancer translates into a longitude of 105 degrees 17 minutes and I found it virtually impossible to understand why he claimed that longitude until I noticed he said tropical longitude. I had the faint recollection of him mentioning his use of the sidereal zodiac in the preface, (at the other end of the book and read several days prior). So I checked the difference between the Krishnamurti sidereal Vernnal equinox and the tropical vernal equinox and found that the difference was 23 degrees 56 minutes, whereas in the calculation the difference is 23 degrees 8 minutes - so the next issue was to explain the discrepencey between the two 'differences'. The answer is that the person was born about 57.6 years ago. Remember that precesion is a continuing phenomenon. And this precession over someone's life has the same impact on PDs as it does for Solar Returns

It became clear that in order to do the calculation it's necessary to convert sidereal longitude into tropical longitude, because of the nature of the spherical geometry involved.

Now if I'd not waded into the calculation line by line, I'd not have become confused and tracked it down to Gansten's use of sidereal charts and the need to convert to tropical in order to do the maths. But as you're mathematically inclined (like me) you may well come across the same headache LOL.
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