Polar Alignment Questions...

[Shaun_Astro]

I have the position of polaris on my phone. But when I look through the polarscope, the 12oclock doesn't point up, and it's about 30deg rotated. Do I rotate the DEC axis it so 12oclock is pointing upwards? Or this this an issue and that should be pointing upwards when the mount is in parked mode? 

[Tomatobro]

Its been a long time since I used a polar scope but from memory your app is showing the position of Polaris as if it were on a clock face i.e. 12 o'clock (at the top), 3 o'clock at the right, six at the bottom etc.

In the polar scope you have a cross in the middle, an outer ring and a tiny ring positioned somewhere on the outer ring. This tiny ring has to be positioned to the same point on a clock face as per your app i.e. if Polaris is at 3 o'clock in the app then the ring should be at 3 o'clock (using the centre cross as a reference). You rotate the axis to put the ring to this position.

Now find Polaris by adjusting the left right and up down screws and position Polaris so its inside the little ring.

Hopefully someone will come in if I have got it wrong.

Remember that the polar scope should be calibrated so the the centre cross stays on an object when the axis is rotated. This is best done in the daytime using a distant object.

[Adreneline]

I used to own an NEQ6 and I rotated the DEC axis so the 12 o'clock position was at top when I looked through the polarscope; in fact I made myself a little index mark with a permanent marker so I knew how far to rotate the DEC axis.

I now own an iOptron CEM25-EC and the 12 o'clock position is at the top without me rotating the DEC axis.

I would say you need to rotate the DEC axis and then use the alt and az bolts to position polaris as per the display on your phone app.

It works for me!

HTH

[Shaun_Astro]

Thanks for the replies. I did angle 12o'clock to the top, then used SAM APP to show where polaris should be. I got it smack on there.

I did just get sharpcap PRO and used the polar alignment feature with my guidecam to check the position. I was about a minute and a half out. Managed to get it just under a minute with it, the bolts are too sensitive. 

At least I know I was doing it correctly!

[Jiggy 67]

If you level the mount as best as possible, then place Polaris in the centre of the polar scope, you can then move Polaris to the top of the circle USING ALT BOLT ONLY, Polaris is now at 12 O’Clock, just move the RA axis to put the scope 12 o’clock on Polaris and lock the clutch.  your polar scope is calibrated. Then carry out PA using whichever app/method you use

Edited March 24, 2020 by Jiggy 67

[Guest]

Isn't it the RA axis you have to rotate in order to get the polar scope reticule in the right orientation?

I have an HEQ5. I have to rotate the dec axis so that the polarscope is open and I can see through it. Then I rotate the RA axis to get the 0 on the reticule at the top.

I think.

[Jezphil]

On 24/03/2020 at 17:03, Jiggy 67 said:

If you level the mount as best as possible, then place Polaris in the centre of the polar scope, you can then move Polaris to the top of the circle USING ALT BOLT ONLY, Polaris is now at 12 O’Clock, just move the RA axis to put the scope 12 o’clock on Polaris and lock the clutch.  your polar scope is calibrated. Then carry out PA using whichever app/method you use

Brilliant. Thanks for this. I've been googling everywhere and this finally provides a solution to an issue I've trying to solve. Now I know it, this seems so obvious but I would never have figured it out without your post!

[AstroMuni]

On 23/03/2020 at 20:19, Shaun_Astro said:

Thanks for the replies. I did angle 12o'clock to the top, then used SAM APP to show where polaris should be. I got it smack on there.

I did just get sharpcap PRO and used the polar alignment feature with my guidecam to check the position. I was about a minute and a half out. Managed to get it just under a minute with it, the bolts are too sensitive. 

At least I know I was doing it correctly!

HTH 🙂

[Martin AB Cohen]

Hi there.  You might find my Polar Alignment tutorial video useful.  Here's the link....

https://www.youtube.com/watch?v=AlCq_TDYDGg&t=25s

 

[dannybgoode]

Just a quick note as I can’t see it’s been covered. To polar align you don’t need to rotate the reticule so that 12is at the top rather you just use the top as 12 if that makes sense. 
 

It doesn’t matter whether it’s 3, 8, 9.45 or whatever, you just line Polaris up so that it matches the position shown on the app and you can ignore the numbers printed round The reticule. 

[Gasconman]

On 10/08/2020 at 19:31, Martin AB Cohen said:

Hi there.  You might find my Polar Alignment tutorial video useful.  Here's the link....

https://www.youtube.com/watch?v=AlCq_TDYDGg&t=25s

 

Martin, this video is by far and away, the best explanation of polar alignment I have seen (and I've seen a few this last week!). I've posted the following as a comment on your YouTube channel, but I'll duplicate it here as it may be of interest to other newbies, like me...

I'm a retired professional photographer but I'm completely new to viewing night skies and astrophotography. I'm expecting delivery of my first telescope tomorrow. Your video is the first I've seen that gives a totally clear explanation of all that's involved with polar alignment, so thank you very much for that. The graphic of the Earth's rotational axis shown at the beginning is brilliant. The only question that remains for me is, what if you don't have a polar scope? I've ordered an Orion 07020e 9x50 right angle finder with corrected view ('erect' being the correct terminology?). This has illuminated cross hairs, but it doesn't have the circles shown in your video. How would I use this to get exact polar alignment?

Second question, to which I can't find an answer, once I have polar-aligned correctly, if I then move the rig to a nearby spot (say within 50 metres) and make sure that the mount is again exactly level, is that OK? Or do I have to re-align the rig every time I move it?

Edited August 16, 2020 by Gasconman
Spelling error

[Tenor Viol]

3 hours ago, Gasconman said:

Second question, to which I can't find an answer, once I have polar-aligned correctly, if I then move the rig to a nearby spot (say within 50 metres) and make sure that the mount is again exactly level, is that OK? Or do I have to re-align the rig every time I move it?

Yes, if you move the mount, which includes knocking it accidentally, you have to re-align.

[Jiggy 67]

3 hours ago, Gasconman said:

How would I use this to get exact polar alignment?

You can’t that I’m aware of, unless you’re using a camera and some form of software but I’m no expert in that. What mount have you got? On an EQ mount PA is about aligning the RA axis of the mount with the North Celestial Pole. For that, without electronic means, you need a polar scope for accurate pa. For visual observations you can get away with pointing the mount North but don’t expect accurate polar alignment.

[michael8554]

Hi Gasconman

If you're only doing Visual, looking through eyepieces, then roughly pointing north will be good enough.

PA only becomes important if you want an object to stay exactly in the middle of the Field of View for a long time, as in Long Exposure Astrophotography.

You can get very good PA by Drift Aligning with only a high mag eyepiece, ideally one with a reticle to aid centring.

Michael

[Gasconman]

8 hours ago, michael8554 said:

Hi Gasconman

If you're only doing Visual, looking through eyepieces, then roughly pointing north will be good enough.

PA only becomes important if you want an object to stay exactly in the middle of the Field of View for a long time, as in Long Exposure Astrophotography.

You can get very good PA by Drift Aligning with only a high mag eyepiece, ideally one with a reticle to aid centring.

Michael

OK, thanks; I'll investigate that

[Gasconman]

18 hours ago, Jiggy 67 said:

You can’t that I’m aware of, unless you’re using a camera and some form of software but I’m no expert in that. What mount have you got? On an EQ mount PA is about aligning the RA axis of the mount with the North Celestial Pole. For that, without electronic means, you need a polar scope for accurate pa. For visual observations you can get away with pointing the mount North but don’t expect accurate polar alignment.

It's a Skywatcher EQ2 mount