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Rob Astro

EQ Polar Alignment Question

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Posted (edited)

I have a skywatcher HEQ5 pro. My question is after polar alignment I return the mount to the home position, should ploaris be in the center of the eyepice? If it's not, can I release the clutches and get polaris in the centere of the eyepice before starting a 3star alignment with the StynScan hand controler.  I polar align always taking care to level the mount and getting polaris in the correct position on the clock.  I find that when trying to star alingnment the stars are always abou 5 degrees out? I hope im making sense my concern is, Is my polar scope and telescope not in line with each other? Thanks for any help.

Edited by Rob Astro
typo

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Posted (edited)

I am fairly new to all this but as far as I am aware you are aligning the centre of the RA axis with North Central Pole point (NCP). As Polaris is slightly off this point I guess depending on the FOV of the lens you have attached you may not be able to see polaris at all in your main telescope directly after polar alignment, but it should be pointing roughly towards it.

I think sometimes my HEq5 has to move both RA and Dec axis quite a long way to actually get Polaris in centre of view due to where it is in relationship to the RA axis.

Somebody more advanced will probably explain much better than I can.

Steve

Edited by teoria_del_big_bang

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Posted (edited)

I too use an HEQ5 PRO and the Synscan, and after polar alignment and then returning the mount to home I've never checked where Polaris is in the main scope nor frankly thought of looking because after choosing the three-star alignment the first star is always in my field of view and I have no problem completing the entire procedure. You must release the clutches to home the mount, and once done, that position should not be tampered with, so where the pole star is in the scope at that time is where it should be. I don't even take the cover off the scope until I get to the first of the three-star alignment. Remember, that first star will almost certainly end up well off centre or even out of the field of view, which was what I was dealing with before my alignments got better, while the next two should be closer. Once the mount has computed the triangulation of the three stars you should be good to go. The real test is how your subs look.

Edited by Seanelly

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Been southern hemisphere, do not have a southern star like Polaris northern hemisphere

The north leg, also has to face south

I align the mount, using a compass, South Celestial Pole, allowing for magnetic variation, where I am is roughly 10 deg east

Then do 2 star alignment

Always pretty close to spot on when go to my first object, be planet of deep sky object

Mount tracks truly 

John

 

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20 hours ago, Rob Astro said:

I have a skywatcher HEQ5 pro. My question is after polar alignment I return the mount to the home position, should ploaris be in the center of the eyepice? If it's not, can I release the clutches and get polaris in the centere of the eyepice before starting a 3star alignment with the StynScan hand controler.  I polar align always taking care to level the mount and getting polaris in the correct position on the clock.  I find that when trying to star alingnment the stars are always abou 5 degrees out? I hope im making sense my concern is, Is my polar scope and telescope not in line with each other? Thanks for any help.

It shouldn't be in the centre of the eyepiece.  I've attached a screenshot from Cartes du Ciel.

The NCP is at the centre of the two circles.  Polaris rotates around the NCP roughly every 24 hours.

The circles represent the view through a 25mm eyepiece that has a 52 degree field.  The smaller circle is with a 2000mm focal length scope, and the bigger circle is for 850mm.

These circles will only be useful if your OTA is mounted parallel (orthoganal???) to the mount.

You can loosen the clutches to rotate the mount to correct the "home" position, but I don't think that it would be worth it if you are setting up the tripod every session.  However, if you do find that it is correct one night, then put a couple of pencil marks on.

 

 

 

ncp.jpg

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You setup should be pointing at the ncp and not Polaris.. Polaris is something like 40 arc mins away from the ncp, so as you're doing the alignment in the polar scope is fine..Polaris won't be in the fov through your scope..

Star alignment is for your pointing accuracy,  how are you doing this? If you use a cross haired ep the accuracy will be far better..think I use 2 star plus 4 calibration stars, might be different with your mount..

Maybe something else to concider is cone error but start off trying the above first..

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