Source of polar alignment error in SharpCap?

[Borodog]

Greetings. I'm wondering what are the potential sources of polar alignment error in SharpCap?

Specifically, when I use SharpCap to polar align, I can get the reported error down to a few arc-seconds. However, when I then guide in PHD2, the drift in DEC is obvious. PHD2 might (for example) measure the polar alignment error at around an arc-minute, which is much larger than what SharpCap reported.

What might be some potential sources of this kind of discrepancy, and how can I mitigate them?

Thanks,

Mike

[admin]

Hi Mike,

the first place to start would be to take a look at this if you haven't : https://docs.sharpcap.co.uk/4.1/#I%20ge ... %E2%80%99t!

Any flex as you rotate the mount can contribute to incorrect results...

I have also wondered whether the movement of the mount to point at different co-ordinates may sometimes have an effect - even if the mount is perfectly balanced around each axis, there are still torques applied at right angles to the axes by the load on the mount, and as the mount moves those torques may change and either flex the whole mount or cause the tripod to shift subtly.

cheers,

Robin

[Borodog]

Thanks, Robin. I bet you are correct about something shifting or flexing somewhere due to rotation. Now that I understand it I can test for it. Then the trick is how to mitigate it.