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MeSeany

Elusive Polar Alignment

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Last time I went caravanning I took my 8" newt - not the most mobile of scopes.

Next week Ill be taking my 80mm apo and newly acquired 150 mak :) - Id love to try some deep space with the eq5 pro and 80mm but last time I tried to polar align it was pitiful.

Id wait until dusk so it was light enough to see through my mounts polar scope but dark enough to see polaris - just one problem though - I could not see polaris through the polar scope... I find locasting Jupiter with my normal scopes hard enough so trying to find polaris with a polar scope was impossible - what am I supposed to do - start lifting the entire mount around as i hunt for a small star with a small apeture - how is this possible?

Then once I do find polaris in the polar scope - how do I turn the mount so that polaris sits in the right place on the circle?

Gees :/

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First, when setting up level the top of the tripod carefully in E-W direction (you did bring a compass of course). In N-S close is ok as that will be corrected soon. Also get the tripod pointing North by compass (allowing for magnetic offset). Set the mount on with azimuth adjustment pretty near the middle. Confirm that altitude adjustment is correct for your latitude.

At this point you stand a good chance of seeing Polaris in the guide scope, if not on the polar scope.

Apparently your polar scope isn't illuminated, so if you can't see, turn on your flashlight, mostly cover the end with your fingers, and move it about in front of front of polar scope. You should be able to get enough illumination to see the reticule without blinding the view.

Taking a hint from the guide scope, move the mount in azimuth until polar scope picks up Polaris.

Use the mounts azimuth and altitude adjustments to put Polaris in the right offset.

If you've done a proper PA prior, altitude should be very close, so start with azimuth.

The Ioptron polar scope is illuminated. I've read that it can be fitted to other brands as well, unconfirmed.

Clear Skies-Jack

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If your polar scope has a rotating eye piece you need to adjust that to achieve focus, if Polaris is out of focus you won't see anything. If you can, and it's tricky, look through the polar acope in the fay time at something very far away on the horizon and work out where focus is.

For very accurate polar alignment you need to align the polar scope to the RA axis of the mount - lots about that in here.

Make sure, if yours has one, that the LED isn't on too brightly in the polar scope, else it will flood out Polaris.

I find, if i use a compass (donmt get too near the mount with it as the metal affects it) i can get the RA axis pretty close to The NCP and donmt need to adjust azimuth to get Polaris in the field off biew once i'm at the right altitude); so if you use a compass, then nust use the altitude knob(s) to hunt for Polaris.

Once Polarisnis in the firld of view, fine tube the position with only the azimuth and altitude knobs. If you donmt understand about the transit of polar around the NCP i'd just start by plonking Polaris abywhere in the big circle in the centre. This will very roughly polar align.

It sounds all a faff, but is dead easy. Ideally get someone local to go through it with you in person.

James

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Ditto the above.

I level the mount actually on the accessory tray that attaches to the legs at the top of the tripod. I make sure that all the legs are fully extended and that the tray is firmly fixed. The HEQ5 sadly doesn't have an integral spirit level.

I also make sure that my altitude scale is as accurate as poss as, after the last adjustment, it might have moved a bit.

I use a cracking bit of kit a friend made me to ensure my mount is accurately pointing north. It's a compass on a flat stick that fits on the accessory tray and onto its supporting bolt, or whatever you call it! If you PM me your address, I'll draw around the stick and send you a template. I wish I could post a pic of it but I'm at work. It's brilliant. You just need to buy a suitable compass to stick on.

Then Polaris should be in view.

I use Jason Dale's Polar Finder on my laptop to find where I should position Polaris on the outer circle (its hour angle) or PolarAlign by George Varros on my iPhone. The former needs co-ords in degrees and minutes and the latter needs decimals.

Jason Dale's Polar Finder:

http://myastroimages.com/Polar_FinderScope_by_Jason_Dale/

Then I use the alt and az bolts to position Polaris onto the outer circle at the position shown on the software. Forget the little circle, just ensure your mount is accurately parked as poss. Don't do all the complicated stuff that Astrobaby suggests. There is a tutorial by Dion Heap (Astronomy Shed), on YouTube, to ensure your mount is accurately parked, but I'll have to wait till I get home to put up the link.

I usually polar align without scope and weights as it's easier and less strain on the alt bolts, but then I'm usually on tarmac. If on grass, use something under the tripod feet to stop them sinking in, and double check Polaris's position after attaching the kit.

Good luck!

EDIT: when you watch Dion's mount parking tutorial, he uses an EQ6, which is slightly different from an HEQ5. You mark the dec axis here:

post-1704-0-94741500-1427444056_thumb.jp

Alexxx 

Edited by Astrosurf

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I would like to add that you need a reasonably good compass. I have found many a compass, especially the cheapo, ones can give a false reading when laid on something metallic, like a tray or the mount.

I tend to take a reading of north whilst holding the compass away from the mount before and after.

Good luck and clear skies

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Metal will offset the compass needle so you need to keep it away from the mount, hence my compass stick.

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So would a compass on my smartphone not be accurate enough? Do I need to go and purchase a stand alone one instead?

I have another question for us in the Southern Hemisphere, and i'm sorry if it sounds like a really stupid question, but when polar aligning, the polar scope and mount seem like they're only made to face North. So do i need to position the mount with the North facing leg, South? The Azumuth knob obviously won't turn the mount head all the way around, so therefore it makes sense to me to just move the mount to face the South and follow the regular procedure for alignment, minus polaris.

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Yes - point the leg marked "N (or interpret it as a "Z") south.

I lay a straight piece of wood along the back legs of the tripods and instead align that E-W.

Whist I've got a southern hemisphere polar scope I've never had much luck finding sigma octans so I drift align instead.

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A very simple trick which works well is to shine a laser pointer through the polarscope. This will be directed reasonably accurately by the optics to point where the polarscope is pointing and that gets you close to Polaris without any guesswork. Rather than look through it for the initial adjustments you just look at the laser's beam. This will get Polaris into the polarscope for fine tuning.

Tripod levelling is rather over rated as a requisite. Levelling NS matters literally not a jot because that angle will be defined by your altitude adjustment anyway. Levelling EW really only sets your polarscope reticle to vertical-horizontal. It has no other purpose.

Olly

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Tripod levelling is rather over rated as a requisite. Levelling NS matters literally not a jot because that angle will be defined by your altitude adjustment anyway. Levelling EW really only sets your polarscope reticle to vertical-horizontal. It has no other purpose.

Olly

But I'm not very good at levelling by eye, and it's OK if I'm on a very flat surface, but most of the time the surface is rough, or sloping, so the tripod isn't level N/S, so Polaris can be off. It's only when I started levelling that I could see Polaris immediately!

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But I'm not very good at levelling by eye, and it's OK if I'm on a very flat surface, but most of the time the surface is rough, or sloping, so the tripod isn't level N/S, so Polaris can be off. It's only when I started levelling that I could see Polaris immediately!

True. That makes sense if you're mobile, certainly, because your altitude adjustment should be near enough right once plonked onto a levelled base. However, folks talk about spending 10 minutes on tripod levelling and this, to my mind, is a waste of about 9 minutes.

Olly

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Super. Thanks for the advice all. Now I just need a clear night. Seems there's a curse for anyone with a new scope. It's now been two weeks, and not a day without cloud cover.

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Once Polarisnis in the firld of view, fine tube the position

James

made me chuckle :)

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Did anyone mention you need to rotate the dec axis to actually see through the polar scope, stick your finger down the hole in the front to locate it, but don't rotate it with your finger in the hole an amputate it :eek:

Dave

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Did anyone mention you need to rotate the dec axis to actually see through the polar scope, stick your finger down the hole in the front to locate it, but don't rotate it with your finger in the hole an amputate it :eek:

Dave

Nearly done that!

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Sigma Octans is the proverbial needle in a haystack. Except there's no needle and no hay.

I can see it on a clear night in the polar scope, but any crud in the sky and don't bother.

Have to admit I only did it once then marked my mount as it is on a pier.

This weekend I'm going to a different site so I'll be using it again if it's nice - though the forecast isn't good.

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