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Re: Towards Quick and Easy Polar Alignment for Equatorial-Mount Users in Equatorial-Regions

Posted: Sat May 23, 2020 4:51 pm
by Airconvent
Thanks for sharing hhzhang ... that is indeed detailed! Stay safe :)

Re: Towards Quick and Easy Polar Alignment for Equatorial-Mount Users in Equatorial-Regions

Posted: Sat May 23, 2020 6:07 pm
by hhzhang
Airconvent wrote:
Sat May 23, 2020 4:51 pm
Thanks for sharing hhzhang ... that is indeed detailed! Stay safe :)
Welcome!

Hope everyone here will begin to realise the fact we do have certain advantages over those in other regions when it comes to polar alignment.

Clear skies!

Re: Towards Quick and Easy Polar Alignment for Equatorial-Mount Users in Equatorial-Regions

Posted: Tue May 26, 2020 10:10 am
by hhzhang
Last night tried the quick alignment using the reference scope view image created the other day.

So far so good for my 30s sub exposures at 0.6"/px -- unguided. Stars all are round shape. The clear sky window was short and precious. So didn't bother to check polar alignment using PhD2.

Re: Towards Quick and Easy Polar Alignment for Equatorial-Mount Users in Equatorial-Regions

Posted: Thu May 28, 2020 1:12 pm
by hhzhang
Last night made use of transient not so clear skies to learn and practice astrophotography.

This time round that rig was set up smoothly. And turning the alz and az knobs to align the image took less than 1 minute (or two?)

Later the PhD guiding assistance reported a PA error of 4.1arcmin.

There must be some additional errors in either my image alignment practice or in my operations (did I touch my rig too hard resulting in shift of some part?), or both.

It will only get better than this!

Re: Towards Quick and Easy Polar Alignment for Equatorial-Mount Users in Equatorial-Regions

Posted: Fri Jun 12, 2020 10:29 am
by hhzhang
The wet season persists. At the same time, my telescope is sent back for servicing.

But you know what? I rediscovered the value and fun of my much portable setup including a star tracker and a prime lens+CMOS combo.

Thanks to the works earlier, now I can just simply aim my polar scope on the star tracker at the same spot in the distance. And PA is settled immediately.

I almost have sold the star tracker cheap earlier on. Now I have figured out how to make much better use of it, including a much-needed human-GOTO function out of the tracker. Also, thanks to plate solving, I can verify the result within 3 seconds, and make a fine adjustment if needed.

Re: Towards Quick and Easy Polar Alignment for Equatorial-Mount Users in Equatorial-Regions

Posted: Wed Jul 22, 2020 3:20 pm
by Kenliew
hhzhang wrote:
Fri Jun 12, 2020 10:29 am
The wet season persists. At the same time, my telescope is sent back for servicing.

But you know what? I rediscovered the value and fun of my much portable setup including a star tracker and a prime lens+CMOS combo.

Thanks to the works earlier, now I can just simply aim my polar scope on the star tracker at the same spot in the distance. And PA is settled immediately.

I almost have sold the star tracker cheap earlier on. Now I have figured out how to make much better use of it, including a much-needed human-GOTO function out of the tracker. Also, thanks to plate solving, I can verify the result within 3 seconds, and make a fine adjustment if needed.
Hi Sir, I am a beginner in this. I have bought a star tracker iOptron Sky Guider Pro. So that I can mount my camera on it to take the photos of the stars with long exposure. However, for months, I have failed to get it aligned properly. I have tried to align it approximately to the North, but my problem comes when my compass both on iPhone and the actual magnetic compass keep giving me different direction. Let me explain, when I move the compass near my Star tracker, it pointed to one direction, but when I move the compass away vertically it pointed to another direction. And I am using PhotoPills app on my iPhone and on different days it gives different direction. I cannot see Polar so I cannot point the laser to Polar star. After so many trials, my photo still have star trails. Some time I managed to get lesser star trails. So, I have read your article in this treads, but it is kind of hard to understand as I am a beginner. So I was hoping if you can give me some guidance in how to properly align the star tracker (may be the simplest way) ... I read some using drift method which I totally cannot understand how to do it too. :(. Can advise? Thanks a million.

Re: Towards Quick and Easy Polar Alignment for Equatorial-Mount Users in Equatorial-Regions

Posted: Thu Jul 23, 2020 11:38 am
by hhzhang
Hi Kenliew, I am also a beginner. I was fighting the same problem as you are. These compasses are never to trust but for rough alignment.

Obviously the method described above does not apply to your situation, unfortunately.

If I were you, I would first use Google maps to find any reference object in the true north direction. Or if that is difficult, I would use Google maps to find a reference object (like a wall or a railing whose deviation from the north can be measured on the map), and then use that to align the star tracker/mount --- the idea is that the absolute reading on the compass may not be accurate, but the relative measurement between the reference object and the mount's RA axis direction) can be accurate to 1deg or so after a couple of iterations. That would bring your PA error to under 2deg normally.


If your camera is an astro cam, you can then choose to use the autoguider function on your tracker and PHD2 for assistant polar alignment. Or, Sharpcap's live stacking is another alternative.

Kenliew wrote:
Wed Jul 22, 2020 3:20 pm

Hi Sir, I am a beginner in this. I have bought a star tracker iOptron Sky Guider Pro. So that I can mount my camera on it to take the photos of the stars with long exposure. However, for months, I have failed to get it aligned properly. I have tried to align it approximately to the North, but my problem comes when my compass both on iPhone and the actual magnetic compass keep giving me different direction. Let me explain, when I move the compass near my Star tracker, it pointed to one direction, but when I move the compass away vertically it pointed to another direction. And I am using PhotoPills app on my iPhone and on different days it gives different direction. I cannot see Polar so I cannot point the laser to Polar star. After so many trials, my photo still have star trails. Some time I managed to get lesser star trails. So, I have read your article in this treads, but it is kind of hard to understand as I am a beginner. So I was hoping if you can give me some guidance in how to properly align the star tracker (may be the simplest way) ... I read some using drift method which I totally cannot understand how to do it too. :(. Can advise? Thanks a million.

Re: Towards Quick and Easy Polar Alignment for Equatorial-Mount Users in Equatorial-Regions

Posted: Thu Mar 11, 2021 5:17 pm
by akdwivedi
hhzhang wrote:
Thu Jul 23, 2020 11:38 am
Hi Kenliew, I am also a beginner. I was fighting the same problem as you are. These compasses are never to trust but for rough alignment.

Obviously the method described above does not apply to your situation, unfortunately.

If I were you, I would first use Google maps to find any reference object in the true north direction. Or if that is difficult, I would use Google maps to find a reference object (like a wall or a railing whose deviation from the north can be measured on the map), and then use that to align the star tracker/mount --- the idea is that the absolute reading on the compass may not be accurate, but the relative measurement between the reference object and the mount's RA axis direction) can be accurate to 1deg or so after a couple of iterations. That would bring your PA error to under 2deg normally.


If your camera is an astro cam, you can then choose to use the autoguider function on your tracker and PHD2 for assistant polar alignment. Or, Sharpcap's live stacking is another alternative.

Kenliew wrote:
Wed Jul 22, 2020 3:20 pm

Hi Sir, I am a beginner in this. I have bought a star tracker iOptron Sky Guider Pro. So that I can mount my camera on it to take the photos of the stars with long exposure. However, for months, I have failed to get it aligned properly. I have tried to align it approximately to the North, but my problem comes when my compass both on iPhone and the actual magnetic compass keep giving me different direction. Let me explain, when I move the compass near my Star tracker, it pointed to one direction, but when I move the compass away vertically it pointed to another direction. And I am using PhotoPills app on my iPhone and on different days it gives different direction. I cannot see Polar so I cannot point the laser to Polar star. After so many trials, my photo still have star trails. Some time I managed to get lesser star trails. So, I have read your article in this treads, but it is kind of hard to understand as I am a beginner. So I was hoping if you can give me some guidance in how to properly align the star tracker (may be the simplest way) ... I read some using drift method which I totally cannot understand how to do it too. :(. Can advise? Thanks a million.
thanks hhzhang.. very useful thread for us. I am looking at the star adventurer. It comes with an equatorial wedge with gradings for latitude. Since we are almost at the equator (1Deg something North), how do we set the latitude settings - keep it at zero. Do a rough north alignment either using app or your method of using Google map and identifying a reference pointing to North. Once the rough polar alignment is done, we use guidecam and PH2 to do guiding?

Re: Towards Quick and Easy Polar Alignment for Equatorial-Mount Users in Equatorial-Regions

Posted: Fri Mar 12, 2021 8:31 pm
by hhzhang
thanks hhzhang.. very useful thread for us. I am looking at the star adventurer. It comes with an equatorial wedge with gradings for latitude. Since we are almost at the equator (1Deg something North), how do we set the latitude settings - keep it at zero. Do a rough north alignment either using app or your method of using Google map and identifying a reference pointing to North. Once the rough polar alignment is done, we use guidecam and PH2 to do guiding?
[/quote]

I am using an inclinometer App on my phone to set the latitude. Azimuth is difficult to determine accurately as far as my experiences go -- the digital compass on the mobile phone is quite inaccurate.

I used to do drift guiding. Now I may use PHD2's calibration and drift alignment tool. And then I may do autoguiding -- depends on the sub length and the focal length. Sometimes I may find autoguiding not working well, which means I have to redo the calibration -- if still not good -- do drift alignment again.

If you will revisit the same observation site, you may keep a record of the exact location as well as the view through the polar scope on the mount.


Good luck!

Re: Towards Quick and Easy Polar Alignment for Equatorial-Mount Users in Equatorial-Regions

Posted: Tue Mar 16, 2021 12:06 pm
by akdwivedi
thank you.. extremely useful thread.