Troy some people use the visible planets, some use asteroids, some use hypothetical planets, some use nodes some use the midpoints betwen planets, some use derived positions, some multiply the degrees. There are lots of different ways to view astrology. Light is a particle or a wave depending on how you look at it. Astrology is the same, its a philosophy and is only limited by the practicioner. For instance I'll read a transit the reverse way astrology says you should. I have my own reasons for doing so, and it seems to work just fine.