Polar Scope Reticle Position???

[Mav359]

My polar scope is aligned with my mounts axis but i was just reading a different thread which has given me the impression that with the mount in the home posiion the reticle should show Polaris in the 6 o'clock position, have i missed something?

I always just assumed that if the polar scope was accuratley aligned with my mounts axis that it didn't matter because you just rotate the mount and adjust DEC & RA so polaris appears in the right place on the reticle.

Am i being an idiot???

Cheers

[WaveSoarer]

Mav,

The reticule on the polar scope should have a cross (or similar) right in the centre. If you align this cross-hair on a star (or a distant object in the far distance during the day - which can make things easier) then the cross-hair should stay aligned with the star (object) as you rotate RA. If it drifts then you need to tweak the position of the reticule slightly using the three grub screws that hold it in place. You need to loosen first and then compensate by tightening one of the other screws to avoid over stressing the reticule. By careful tweaking then the cross-hair should be positioned in the same fixed space as you rotate RA: i.e. the cross-hair is now accurately aligned with the RA axis itself.

The polar alignment should be carried out on the circle that is described around the central cross-hair. This circle has a very small target circle on its circumference and the pole star should be positioned within this. You'll need to rotate RA so that this little traget circle is in the right position. The constellations on the reticule should help here or you can use freely available software to get the setting right. As the pole star is slightly offset from the pole it traces a circle around the true rotation centre in the sky and the position you start from will depend on the date and time.

That's pretty much it I think - though you still need to ensure that the base is level before you polar align.

Sorry if this is covers material you already know but this is how I do it.

Dave

[WaveSoarer]

Mav,

The reticule on the polar scope should have a cross (or similar) right in the centre. If you align this cross-hair on a star (or a distant object in the far distance during the day - which can make things easier) then the cross-hair should stay aligned with the star (object) as you rotate RA. If it drifts then you need to tweak the position of the reticule slightly using the three grub screws that hold it in place. You need to loosen first and then compensate by tightening one of the other screws to avoid over stressing the reticule. By careful tweaking then the cross-hair should be positioned in the same fixed space as you rotate RA: i.e. the cross-hair is now accurately aligned with the RA axis itself.

The polar alignment should be carried out on the circle that is described around the central cross-hair. This circle has a very small target circle on its circumference and the pole star should be positioned within this. You'll need to rotate RA so that this little traget circle is in the right position. The constellations on the reticule should help here or you can use freely available software to get the setting right. As the pole star is slightly offset from the pole it traces a circle around the true rotation centre in the sky and the position you start from will depend on the date and time.

That's pretty much it I think - though you still need to ensure that the base is level before you polar align.

Sorry if this is covers material you already know but this is how I do it.

Dave

That should be reticle of course - doh....

[steppenwolf]

I always just assumed that if the polar scope was accuratley aligned with my mounts axis that it didn't matter because you just rotate the mount and adjust DEC & RA so polaris appears in the right place on the reticle.

Almost!

After you have aligned the polarscope with your RA axis, the orientation of the polarscope's crosshair at the park position is immaterial. When you polar align, you adjust the RA axis to position the polarscope at the right orientation and then adjust the azimuth (left and right) bolts and altitude (up and down) bolts to centre Polaris in the little circle etched on the polarscope's reticule.

[dmahon]

The base doesn't need to be level.

We all make sure that our polar scopes is tweaked as described, but if it comes from the factory like that, how do we know that the polarscope has been put in the mount in the correct orientation in the first place? If I hasn't the computer software (or using the setting circles as described in the manual) won't work, will it?

[JamesF]

As Dave says, the mount doesn't need to be level at all. Adjusting alt and az will take care of any lack in that regard. It may be useful to get it close because you can set the latitude setting on the alt scale and hopefully you should see Polaris in the polar scope, but it's no big deal if it isn't.

Once the polar scope is aligned so that the centre of the cross doesn't move when the mount is rotated in RA, I think the easiest way to get the reticle in the right position for Polaris is as follows:

During the day, if you can, point the polar scope at something you know to be vertical and get the centre cross aligned with the vertical. If you don't have anything vertical you can do it by eye. Rotate the RA axis to set the time and date rings to midnight on 1st November and lock the RA axis. This is when Polaris is highest above the NCP. Because the polar scope inverts the image Polaris should therefore show as low as it can possibly be. That's going to be below the cross, on the same vertical line. So, rotate the body of the polar scope (not the RA axis) until that's where the Polaris indicator on the reticle appears.

That's it. No computer required, no guesswork estimating the position of Polaris (unless you can't find a vertical, but that is much easier to estimate than the position of Polaris on any other date).

James

[Mav359]

Almost!

After you have aligned the polarscope with your RA axis, the orientation of the polarscope's crosshair at the park position is immaterial. When you polar align, you adjust the RA axis to position the polarscope at the right orientation and then adjust the azimuth (left and right) bolts and altitude (up and down) bolts to centre Polaris in the little circle etched on the polarscope's reticule.

Thats what i wanted to hear, my polarscope is lined up with the axis no probs using the TV ariel method (Dion @ AStroshed's video) so i know thats spot on but the other post i read started making me think that the reticle needed to be re-oriented as well. Cool beans i am doing it right then

[Essex Stew]

sorry to drag this back up, BUT when I rotate my EQ5 GoTo RA axis to line up polaris, the DEC motor casing clashes with the RA motor casing,and im unable to get polaris in the small circle due to no more movement available. Am I doing something wrong? I am fairly new to this as my previous mount was a EQ2.. Please help

[Astro_Baby]

Essex - how about if you rotate the mount the other direction towards POlaris ?  Do you have this clash for both directions - its doesnt matter whether you go clockwise or counter clockwise in this respect.  Also can you shift the DEC axis round so that its out of the way.

Some mounts do cause this but usually you can shift round it by moving the DEC axis and/or rotating the RA on side or the other.