Polar alignment

[stovesy]

 

I'm getting ready to position some slabs for standing my eq mount on.

Ive got the mount generally pointing north, and level, but before I actually cement and fix the slabs, I want to have a go a polar aligning using the built in scope so I know that things are generally in the right place.

 

But

 

I've have no clue as to how to go about this.....

 

The polar scope has a graduated rotating ring as I hope the picture shows, and looking through the scope I see a trapezoid shape with a small scale (40-60) above.

 

All very complex.

 

It's an Orion LX200 scope and I've heard to Vixen word mentioned when it comes to the mounting.

 

Any pointers would be much appreciated.

[dawson]

I'm no expert and still learning, but the view of your polar scope looks similar to others, in that the centre has a cross (which will represent the northern celestial pole when it's finally aligned) and there is a small open circle which you'll need to get Polaris to sit in, by altering the alt and az bolts (once the scope is levelled). The line with the circle for polaris should rotate around the cross when you rotate the scope around the RA; you'll need to have this line pointing at a specific time on an imaginary clock face for your polar alignment to work, there are various websites and free apps which tell you where the line should be pointing at the time you set up your kit (it changes continuously and eotates a full 360 every 24 hours (well 24 hours minus 4 minutes ish).

Are you near compton acres? If so i can come and try and help [hinder] sometime.

James

[dawson]

This image:

 

http://www.southern-astro.com.au/imgs/guides/lx200gps/polaralignment/050601SouthPole.jpg

 

might suggest your polar scope has a southern hemisphere reticule in it... Though again as I say, this is not my area of expertise.

 

James

[philjay]

I reckon your right there James, looks to be a southern hemisphere reticule. The mount from what I can see Pete appears to be a Vixen or Vixen Polaris or SP clone, its a long shot but you may be able to get a northern polarscope for it from someone who has a dead mount or maybe give Vixen UK a call Im sure they would help

[dawson]

I accidentally took my polar scope arpart and the reticule just fell out, so maybe if it is a southern hemisphere reticule, you could get a replacement reticule for the northern hemisphere. But you'd need to know exactly what the polar scope is.

 

James

[stovesy]

I got the scope second hand from a guy I know, and it's been setup and aligned before. Maybe it's got markings for both hemispheres.

 

I've just read that Polaris is 'approx 45 arc minutes from the true pole'  So... looking at the image through the polar scope, the little circle is around 45-ish away from the cross on that scale.

 

James. I'm near to the middle of west bridgford, and thanks for your kind offer. I will try my luck on the next clear (and dark) night - if we ever get any, and post my results.

 

I'll let you know

 

Thanks

Edited July 17, 2013 by stovesy

[dawson]

I'd have a play with it in day light, see if you can work out if the reticule can do both hemispheres, you'll need to check if the polar scope is aligned with the mount anyway in day light, I've got some screws with thumb grips on which will make aligning the polar scope to the mount easier anyway, and that is a job which is easier to start doing in day light, then finishing it off at night.

 

There may be some way to fudge a southern hemisphere reticule to work in the northern hemisphere; you'll have to do a google search.

 

I'm happy to help at some stage if I can.

 

James

[stovesy]

Found this....

http://www.company7.com/library/vixen/VixenNAGP_GPDX_PoleAlign+Findr.pdf

[dawson]

"Dear Vixen

A friend has this mount and the polarscope appears to have a southern
hemisphere reticule in it. is it possible to replace the reticule with a
northern hemisphere one?

Regards

James Dawson
Nottingham"

 

and their reply:

 

"Hi James

Thanks for your email.

The reticule can be replaced. The price for a replacement is £25 including
VAT and delivery. The item is in stock.

You need to call the office on the number below to order with a credit or
debit card.

Best regards, Pete


Pete Gamby
Sales and Marketing Manager

http://www.opticron.co.uk
http://www.vixenoptics.co.uk
http://www.facebook.com/opticron
http://www.twitter.com/opticronuk

Tel: +44 (0) 1582 726 522
Fax: +44 (0) 1582 723 559"

[stovesy]

It's a done deal. Will call them tomorrow.

 

Thanks for your help.

[dawson]

I looked at the link you posted, and it seems there is a way, maybe, to use the reticule you have for polar alignment in the nothern hemisphere. I read it quickly at work and it was confising me, but it might be possible. The replacement reticule the guy talked about in the email may look exactly the same, so do do uour homework before shelling out £25 for exactly the same reticule. And ifbyou ofer it make aure you give them the exact details of your polar scope so you get he correct one.

I don't want to get the blame for giving out duff information.

James

[Guest CodnorPaul]

Reading this puts me right off an eq mount when I was considering one   well confused!  Is it really that hard?

[dawson]

No. Not at all. I seem to be able to manage it, and it is so much more straight forward than it reads.

I can show you sometime.

Essentially the equatorial mount can move in four planes; they can be moved slightly in an alt and az axis, and then majorly in an RA and declination axis.

Point the polar scope at polaris by positioning the mount.

Then use the alt and az adjusters to get polaris exactly in the correct place in the polar scope.

Then it's polar aligned, and any subsequent movement of the scope uses the RA and declination axes.

Easy.

Jd