Pin-sharp accurate polar alignment

Keith,

I use WCS Polar Align. It works with a simple webcam and gives you a very accurate drift alignment in minutes. (once you got if figured out).

wcs.ruthner.at/index-en.php

Basically you connect the webcam, point at a bright star in the south. Allow the software to measure the drift for a couple of minutes. The software then tells you which way to turn the knobs. You repeat the exercise for a star in the east. I highly recommend it. Once you got the hang of it its a doddle.

I have that Dave and it works very very well. Very easy to use.
I do wonder if polealignmax is any more accurate?

I do wonder if polealignmax is any more accurate?

At the risk of starting a flame war, I suspect PAM does a better job since it uses a CCD camera as opposed to a webcam. I have much more confidence of a stellar disk from a CCD image as opposed to a webcam image.

Anthony,
The last time I looked at Polealignmax, it needed Pinpoint. If I understand correctly, The Sky will now suffice and there is no need for Pinpoint. Is that correct?

Absolutely. TheSky is sufficient if you have it OR you can use the GSC1.1 catalog and provided the ASCOM driver is loaded as well.

PAM indeed does a great job - within an arcminute or so of the pole. Manual drift align then get me within arcseconds of the pole - yes, it is time consuming etc but once its done, grand for a month or two.

I think PAM lets you do alignment from pretty much anywhere in the sky. I'm assuming it then does some calculations based on where your scope is saying it is pointed, where it is actually pointed (based on a catalogue) and then what the polar offset is. So I guess to an extent it is relying on the accuracy of the co-ordinates given by your mount and the accuracy of the catalogue.

Drift alignment (I think) would only rely the mechanics of your mount, OTA and mirror etc (e.g. orthogonality, flexure, mirror flop etc), not the accuracy of third party data. I could be wrong however...

So I guess to an extent it is relying on the accuracy of the co-ordinates given by your mount and the accuracy of the catalogue.

This would of course apply to any software-based approach.

Anyway, I feel very confident that my AP1200GTO does a really good job in knowing exactly where it is pointed (vis a vis the feedback it provides to PAM) and certainly I can trust the GSC catalog which is a subset of the USNO catalog.

Just to give you an idea, when I used it about two years ago upon the arrival of my AP1200GTO, as a side product, it reported that the focal length of my AP160 was 1202 mm ... in theory it is 1200 mm but I will allow the extra 2 mm due to focus with the CFW10 attached.