russell bob - 2013-06-25

Hi, I was using the polar alignment tool last night but ran into some issues with the repeatability of the measurement.

I started with checking Azimuth and pointed the scope south near the celestial equator and meridian intersection. I ran the tool 3 times without making any changes to the mount. I noticed a difference of about 3-4 arc minutes between each result.

I then did the same for altitude, this time moving the scope to the East and pointing as low as possible. This time, I was getting a difference of around 5-6 arc minutes across the 3 measurements.

Is this expected behaviour or should I be getting better repeatability?

My mount is an HEQ5 and the scope was a Skywatcher 80ED with 0.85x FR/FF. Camera was a Canon 1100D. I used APT to capture the images.