Just my opinion, but to simplify Gann's research and methodology down to Astrology would be doing him a disservice. Gann was researching harmonics and its effect on the world around us and us. A good book to look into for an introduction is "All About Technical Analysis" by Constance Brown. She discusses Fibonacci, Gann, and harmonics all throughout the book, but Gann comes in primarily in the last few chapters. If you're going to google harmonics, make sure you look for Pythagorean Inotation and not Equal Temperament. Equal Temperament is the harmonics related to European and American musical scales and not mathematical harmonics(phi). Also, look up the Gann Harmonic Wheel. It's really interesting and has links back the to building of the Pyramids in Egypt.

Mookfx