Hello from California. Hope things are good there in Berlin. I also haven’t found much. A document that describes negative parallax and says to take the average of the positive parallax and replace it when you measure any negative parallax. hence allowing a precession like motion where I believe it may reset. 30 year observation of Polaris would show a lot but even that is hard to get. It’s all in books. It was here. But even the Almagest is a forgery in parts. They can change whatever whenever.