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Polar alignment just once or do you have to do it again and again?


asteele3
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I finally tried on my 4th attempt in 2 months to do the polar alignment and this time when it was doing the first star alignment on Alkaid, I was nervous but this time it went right near it so the star was about 2 cm off from the centre of the cross in the finderscope. I think I could have nailed all the stars last night if it'd not been for the fact that the finderscope and the telescope are both working in syncrony yet. However, when I do get everything working right, do I have to do the 3 star alignment each night? Or would I just need to put the tripod north and then star from there?

Thanks,

Andrew.

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If you move the tripod then you'll need to repeat the polar alignment procedure.

James

... and then do the 1,2 or 3-star alignment. This is one reason why an obsy is such a great idea ;)

Edited by Black Knight
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Actually, I have probably been misleading there.

If you move the tripod then either you can repeat the polar alignment, or you can do a three-star alignment. You shouldn't need to do both. There's a bit more to polar alignment than just getting Polaris in the circle though -- you have to make sure first that the circle is in the correct place, which firstly means checking the polar scope is properly aligned with the RA axis of the mount and then that the reticle in the scope is correctly oriented for the date. Have you done that bit?

James

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So I just have to get polaris in the little circle and it should all be good? Because doing the 3 star alignement will take me ages avery night!

What is it that makes the three star alignment take so long? For me, it takes less than two or three minutes (and that's because I'm using my camera at high magnification to make sure that the star really is in the middle of the field of view).

Edited by olander08
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You will need to do the Polar Alignment and star align each session. If you are doing astrophotography and will be working on just one subject each session then a 1 star alignment is all you need (providing the star you choose is close to your imaging subject!) but if you are observing a range of objects in different regions of the sky then you need to do at least a two (and preferably a three) star alignment to 'map' your mount to the whole sky.

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Hi Andrew, just reading this and I'm not sure if you are getting mixed up with polar alignment and GOTO alignment. The 3 star alignment will just get the GOTO accurate. Polar alignment is completely different and aligns the mount. Sorry if I have read this wrong and you are aware of this, just wanted to be sure.

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For visual observing, pointing close to North is good enough. Close polar alignment is only really needed for astrophotography.

Having said that synscan, syntrek etc. need closer polar alignment for them to work properly. Does take time - hence I built an obsy.

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Are you actually guiding, using a guide camera on a guide scope,, or are you depending on the mounts Ra drive to track your target.?

Electronic guiding can compensate for Polar Alignment anomalies within reason, but if not then you need to keep exposure quite short if you are depending on the mount tracking alone.

I'm assuming because you have cameras, that you are imaging, and not just observing. :smiley:

Ron.

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Well for now I'm just observing as I think imaging is only going to happen from late september/october onwards!

And thanks Freddie, it helps never the less!

I've probably only had about 5 clear nights in about 7 weeks so not been able to do much to it recently. Although I'm still learning and I feel I'm getting there! Especially last night when I finally managed to get it near the star in question when I ran inside and slammed the door to go and yell 'YESSSS', I think I may have woke my neighbours up!

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It's just struck me that when doing a 3-star alignment you really do need to be sure that the stars you're pointing the scope at really are the ones you think they are, otherwise it won't go well. I know it sounds a bit daft, but whilst it might be easy if you have clear views of the sky it's not necessarily so if there are trees or houses obscuring some of your view. There was someone recently who was unhappy because he couldn't see any rings around Saturn until we eventually worked out that Saturn was actually below the roof of a neighbouring house and what he thought was Saturn was a bright star nearby. It's easy to make such mistakes if you don't have enough information to go on, and all to easy not to realise that you don't have enough information to go on :)

James

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Even when the star alignment failed, lol, when I selected it to point at Mars, it went straight to it because it was just going down over the horizon! Just got to wait for when and if the summer actually starts and to finally get a string of clear nights in a row and not just the odd one in a month!

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And I use Stellarium and Red Shift Planetarium to locate which stars I want to look at! I did it on Alkaid and then Vega. Great to see the goto finally starting to go to where I want! Love the scope and the mount.

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Are you setting up in the same place every time ?

Before I built my obs'y I had three locating holes in the ground so I set up with the tripod in the same spot every time .

Saves a bit of time,

Davey-T

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