There has been several discussions on the Aladin software at Ice in Space. You might like to look at the ISS thread "Position angle calculation."
I posted an example of using Aladin and how to do positional stuff on images (downloaded and observer's images)
"
Using ALADIN for Calibration of Personal Images" [* Post#16 CalibSepPA1.pdf ]
See
http://www.iceinspace.com.au/forum/s...ghlight=Aladin
However be aware there are other softwares, but I still find it best for my purposes.
Cheers
