Polar alignment on repeated nights

[mindburner]

Hi

 

I currently us a pier mounted EQ 6 with eqascom to polar align.  This is a great method and I carry it out each observing session.  

 

I stumbled across a sky at night article on diy piers and they were saying that polar alignment needs only to be done once.  Hmm I though, surely even with eqascom if the mount is powered down, adjustments still need to be made using the bolts.

 

Basically I want to not have to fiddle with bolts night after night and was researching motorised options. A mini remote obsy with a 200mm camera lens is my end objective and remote polar alignment would be great. I don't really have the clear nights for drift alignment or anything.  

Something like the avalon range of kit would be fantastic but it's 10000 euros 

If anyone can confirm that there is such a thing as one time polar alignment on a pier, that would be great as it sounds too good to be true to me.

Thanks 

 

 

[DaveS]

I would have though that if your pier is solid and you have the bolts locked tight after PA then you would only need to check every so often, perhaps once every two or three months, or after a major change of kit.

If you're having to re-do the PA every time you power up, then I would think something's wrong somewhere.

[Helite]

You say you already use a pier, but that you carry it every night? I am going to go out on a limb here and guess you mean pillar mount instead of tripod type?

 

Edit: Re-reading your post I think you mean "carry out" your polar alignment routine each session and not carry out a mount as in from inside to outside. Silly me.

 

[Tinker1947]

If the pier is unmovable and the mount is not removed then PA should be good once its been done for several months getting it spot on may take a few attemps drfit aligning, or if you have a Syscan Handset the PA option built in will get it close to perfect.

[mindburner]

hi all thanks for the replies. II should clarify that I have the large metal pier permanently set up and roughly pointed at Polaris. The only kit I attach is the imaging setup. Either a 127mm scope with weights or a canon 200mm lens and ccd. I as under the impression that it is the mount that is aligned and this can only be done via the physical bolts on the mount. As Polaris shifts around the NCP then the physical mount must be moved via the bolts?

When i'm finished imaging, the mount is polar aligned and then parked to home position. Even so surely I still have to manually adjust the mount for the new position of Polaris next imaging session. 

I guess i'm aligning for Polaris rather than true NCP maybe that's the issue

thanks indeed

 

[DaveS]

Yes, that's exactly the problem. Polaris is about 1 degree from the true pole so you'll also be getting field rotation.

As you have an EQ6 with a polar 'scope you can use the Eqmod polar alignment tool to get a rough alignment, then use PHD2 with your guide camera to refine it through several iterations of drift aligning. You can also use APT with your Canon 1100 to drift if you don't have a guide 'scope yet.

If you don't have a guider yet, that should be your next purchase.

[Cornelius Varley]

9 hours ago, mindburner said:

hi all thanks for the replies. II should clarify that I have the large metal pier permanently set up and roughly pointed at Polaris. The only kit I attach is the imaging setup. Either a 127mm scope with weights or a canon 200mm lens and ccd. I as under the impression that it is the mount that is aligned and this can only be done via the physical bolts on the mount. As Polaris shifts around the NCP then the physical mount must be moved via the bolts?

When i'm finished imaging, the mount is polar aligned and then parked to home position. Even so surely I still have to manually adjust the mount for the new position of Polaris next imaging session. 

I guess i'm aligning for Polaris rather than true NCP maybe that's the issue

thanks indeed

 

If you have a permanent setup ie a fixed pier with the eq mount fixed to it and accurately polar aligned then you shouldn't need to polar align every time you use the mount. The mount is aligned on the north celestial pole, not the star Polaris which is close to and rotates about NCP but is only used as a guide for polar alignment.

[mindburner]

fantastic. All this time I have been just redoing the PA as it really is easy with the superb Eqascom. But as I start to look at remote observing I started thinking about it more. I have just started using PHD2 as a guider with a QHY5/50mm finder combo. It works pretty well. I shall check out it's drift alignment routine.

I appreciate all the info.