Using Kochab's Clock for Precise Polar Alignment

[whooshbang]

I'm curious as to how many people here use this method to achieve "precise polar alignment" for their mounts and how they get on with it.

I currently do a rough polar alignment for observing then kick off a session but upon searching for more accurate methods other than 'drift alignment' found these results :

Precise Polar Alignment for GEM mounts

And

Precise Polar Alignment For Fork Mounts

Very intrigued by the apparent ease of this method and about to strip the (nicely) collimated polar scope down to line it up with counterweight bar.

I would love to hear your thoughts and opinions before i do though. Cheers

[stargazerslivingroom]

Found this intriguing, too and it led me here http://www.astrochat.co.uk/forum/viewtopic.php?t=847 very interesting site.

Not sure about your comment about stripping the polar scope down though...Step 1 says collimate it in the usual way. Am I missing something?

Thanks for the info...Didn't know about this and, as I so far only do visual, this will be interesting to try.

[whooshbang]

An interesting method. I think it applies to mounts with no polar scope built in as it uses the main scope to find NCP whilst making adjustments to the mount. This would work just as well i guess but the main OTA would need to be calibrated to the polar axis perfectly for good alignment and possibly setting circles would need calibrating too as they have a habit of shifting when scopes get moved about. (at least on fork mounts)

If you have a Polar Scope built into your EQ mount it would be better to align using this..... that said, calibration of your main OTA to your Polar Axis is still important if you intend to image.

Collimation of the polar scope is another matter all together. There are 3 grub screws that you can adjust to ensure you have the polar scope reticle dead centre in the RA axis. If you centre your polar scope cross hairs with a star, Polaris for instance, and rotate your scope 180 degrees about the RA axis (do this without OTA connected) Polaris should remain perfectly within the crosshair throughout the rotation and not be displaced throughout the rotation of the scope.

If Polaris stays centred on the crosshair your polar scope is collimated. If Polaris moves off the crosshair or is displaced whilst rotating the scope (RA axis), adjustment is required.

I done mine a while back its a bit fiddly i can tell you especially in the dark. One of the above guides explains how to do it in daylight. The reason for striping it down or re-adjusting, for want of a better word, is to line the reticle' crosshair and Polaris to the counterweight bar as described in the GEM alignment method.

Hope that kinda makes sense? i am unfamiliar with this myself so i'm speculating a bit and my head is now hurting

[Graham Darke]

I use Kochabs clock technique with my EQ6 mount which does have a polar scope. It's very quick and gets polar alignment pretty close. I wouldn't say it gave a better results than drift aligning though. Drift aligning is the best way if you're imaging.

[whooshbang]

I use Kochabs clock technique with my EQ6 mount which does have a polar scope. It's very quick and gets polar alignment pretty close. I wouldn't say it gave a better results than drift aligning though. Drift aligning is the best way if you're imaging.

For simply observation "rough polar alignment" does the trick then! But if you are gonna image "drift alignment" is the one. I guess there is no in between and hence no reason to use kochab's clock method.

Leave the polar scope in my neq6 well alone then.

[Tony Rodda]

I'm not sure about other mounts but my CGEM has a polar alignment option using (almost) any star. Seems to work very well if you do it several times using different stars. (The mount is permanently set up).

Regards

Tony