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How can I polar align when my yard faces south? Please don't say PHD2 drift align

Beginner Polar Alignment Software
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#26 unimatrix0

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Posted 21 September 2021 - 01:05 PM

We aren't very far away from more intelligent mounts with better hardware/software built in to polar align itself with its built in mini telescope and camera. It'll probably drift-align via plate solving and turn its own axis to set the alignment and all you gotta do is sit down and slurp some coffee.   Mark my words.. I bet someone is already experimenting with or perhaps there is a prototype already. 


Edited by unimatrix0, 21 September 2021 - 01:07 PM.


#27 algolrising

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Posted 21 September 2021 - 02:37 PM

I'll second the endorsement of the Ekos polar alignment routine. My only view is due south, no prayer of seeing Polaris. After using my iPhone with the Polar Align Pro app, I got somewhat close. The Ekos polar alignment routine got me within an arc minute. It uses three plate solves and projects a solution you use your mount adjustments to correct. I have a LX200 classic on a Milburn wedge, and it was remarkably quick, probably a 5 minute affair start-to-finish. In my particular situation, my MacBook did not want to properly control the LX200 during this operation, but the Raspberry Pi version worked flawlessly. I don't believe my Mac problems were Ekos or INDI related, so I'd not expect anyone else to have a similar problem. I would expect either Linux or Raspberry Pi to work without issue, cannot speak to Windows.

 

Jay



#28 Szumi

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Posted 21 September 2021 - 04:06 PM

In rough order of importance, from most to least.

 

What you describe is not bad polar alignment.  Bad polar alignment causes DEC drift (which can be corrected by guiding, but guiding is imperfect, the less you guide the better).  Or maybe some frame rotation, causing funny shaped stars.  Not chaotic guiding graphs.

 

You need to post _exactly_ what PhD2 is saying is wrong, start to finish.

 

What people used before computers is polar alignment scopes.  But they require a view near Polaris.

 

Almost every good imager uses a computer.  They take the load off you of mundane chores.  They let you point to a target much more reliably than GOTO.  They let you monitor what's coming in.  And they're absolutely esssential for running an astro camera, which has little intelligence of its own.  By the time you use one for all that, using it for good polar alignment is a small addon.

 

Mount level is unimportant, as long as it doesn't topple over.

 

Zero position affects GOTO, not guiding.

 

The three star alignment is not for polar alignment, it's for GOTO.  The Polar Iterate Align is for polar alignment.  It doesn't give you a value or value of anything, you're just trying to center stars.

 

But you have bigger problems than polar alignment.  Sorry.

Please expand on why mount level is unimportant sir.



#29 bobzeq25

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Posted 21 September 2021 - 05:12 PM

Please expand on why mount level is unimportant sir.

Sure.  Once you have the RA axis of the mount pointed at the North Celestial Pole, what difference does it make where the top of the tripod sits?  As long as the scope doesn't fall over.  The pointing of the mount is all that counts, not the pointing of the tripod top.

 

While you are aligning, with some methods, having the mount level helps the alignment process because changing the altitude doesn't affect the azimuth, and vice versa.  Once you are done polar aligning, it's no longer important at all.

 

With my Polemaster, even that is not an issue, at all.  I see where the RA axis is pointed relative to the NCP realtime.  It makes no difference to me at all if adjusting the altitude affects the azimuth a bit.  Things are easy, regardless.


Edited by bobzeq25, 21 September 2021 - 05:23 PM.

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#30 Alex McConahay

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Posted 21 September 2021 - 06:43 PM

>>>>>>Please expand on why mount level is unimportant sir.

 

As Bob points out, it is not important that the mount be level in a polar aligned scope. But, I would say leveling the mount makes the whole process easier. (Yes, Bob slips that in, but not with its proper due, I think.) 

 

If your mount is not level in the first place, every time you adjust one axis you are ALSO moving the other. So you have to go back and forth trying to get both axes right. Sure it can be done. But, it really is easier to get the mount level in the first place. Then do the azimuth. Then the Altitude. If you are level, theoretically, you could be done (except for the inexactitudes of life). If you were not level in the first place, you MUST go back to Azimuth to re-check that. It may be good. It probably is not if you have made any substantial altitude adjustment on a mount head that was not level in the first place. 

 

This "mount does not have to be level" is one of those things that are right, but not good advice. You are better off starting with a level mount. In no case do you need to obsess over the level-ness (what is the word for that?) of the mount.....

 

Alex


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#31 1DegreeN

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Posted 21 September 2021 - 11:08 PM

I would be surprised if this worked reliably? the other thing you could do that may help is to just release one azimuth bolt when you pack away, then when you set up tighten only the bolt which you loosened, but I would always check myself.

It did work well, I have 3 rigs (AZ-EQ5, AZ-EQ6, EQ6R) and used this method for 2 seasons (Oct-Mar), only doing the altitude drift align once at the start of the season. PHD logs show a PA error anywhere between 1" and 8". I leave the mount head on the tripod when I lug the gear in and out of the house and the altitude setting is not disturbed. When setting up, the biggest error is lining up the tripod with the markings and this obviously affects the azimuth alignment. Our neighbours to the north have now bulldozed away the tall bamboos which were obscuring the NCP so from now on I'll be using SharpCap again and it will be interesting to find out what the altitude error is on the first SharpCap PA.



#32 AaronH

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Posted 21 September 2021 - 11:46 PM

Frankly, after aligning using the three-plate-solve technique (as used in Ekos, etc), I wouldn't do it any other way. If my alignment is within a degree or so to start with, I can be done in well under five minutes.

 

It so consistent it's almost boring.




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