Spherical Astronomy by Robin M Green claims to be a updated version of a previous book of the same title that was the standard introductory text on positional astronomy. The claim seems sound. After my math refresher books, I started it again. This time, some concepts started to make sense after a couple of readings. But then the book went deeper and I started to get lost again. So, I ended up skimming the book.
My long-term goal is to return to his book again but I think I have enough theory to get back to the astronomical calculations and then to observational astronomy. But, first more work on the Astronomy Calculator.