I've added a levelling base to my Dob to get better accuracy using the azimuth setting circle, I'd previously had accuracy issues and attributed this to the base not being level hence the modification. Anyway I get out this evening, the first semi clear sky since I finished the base, carefully levelled the base turning the spirit level to ensure everything was done to reduce any chance of errors all good so far. I then fired up Stellarium and looked up the Alt Az for Betelgeuse and adjusted the pointer on my scope base to match the azimuth then spun the scope round to Merak read off the azimuth referred back to Stellarium only to find it was a couple of degrees out. I went back in and double checked the time and location I had set on Stellarium and it was and still is spot on. I repeated this throughout the sky and it was the same story.
I'm back inside now having spent the evening trying to understand the problem, re levelling the base, re checking Stellarium, re aligning and all to no avail, I've even checked the accuracy of my degree circle which is spot on. I then came to the conclusion Stellarium was wrong opened up Skychart checking location and time against Stellarium and both are identical. I then looked at a few alt az coordinates for various objects and found a discrepancy between the two programs with Skychart showing 4 degrees higher azimuth reading than Stellarium exactly what I'd seen earlier with the scope after aligning to Polaris. Thus Stellarium appears to be showing incorrect alt az coordinates.
The obvious answer is to use Skychart but I find the program very clunky when compared to Stellarium so would prefer to find out what's going wrong.
I have another machine running Stellarium and that shows exactly the same alt az as machine number one????
Please show coordinates of location from both computers.