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Old 06-07-2019, 01:51 PM
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EQ3 Pro - polar alignment with the SCP

Hi everyone,

I'm just wondering how do you accurately align to the southern celestial pole (SCP) with an EQ mount? I've only recently got my first EQ mount (EQ3 Pro) and am trying to do that. Using stellarium, southern cross and Hadar and Rigil Kent, I know where in the night sky the SCP is. But when looking through the polar axis scope, there's just a lot of blackness around the SCP, and I'm not confident of the alignment.

I'm assuming roughly aligning it isn't good enough for astrophotography, it needs to be more accurate. How do you all do it?

Thanks!
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Old 06-07-2019, 02:41 PM
Startrek (Martin)
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Check your Synscan handcontroller manual, there should be a feature used for polar alignment when you canít see the SCP
I use it all the time and works well
Cheers
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Old 06-07-2019, 04:32 PM
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I read that you have a polar scope ?
Use the faint BQ Oct and put it in the center of the field.

Here my way to find it: https://www.skysurfer.eu/eqmount.html

That works awesome for me and can make 4 minute subs with 600mm FL without guiding.
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Old 06-07-2019, 05:15 PM
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Quote:
Originally Posted by Startrek View Post
Check your Synscan handcontroller manual, there should be a feature used for polar alignment when you can’t see the SCP
I use it all the time and works well
Cheers
Could you confirm if it's section 11.3 from here - https://inter-static.skywatcher.com/...61208V1-EN.pdf

Because I got it 2nd hand, I don't have the manual with me.
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Old 06-07-2019, 08:18 PM
Startrek (Martin)
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Yes thatís the procedure for PA without a view of the SCP ( all you need is a 20mm wide view illuminated reticle eye piece like an Orion brand ) or later on you can use a software program like BYEOS if imaging with a DSLR or other Astro imaging software if your using an Astro camera. I use a DSLR so BYEOS provides a live view screen on my laptop so Iíve stopped looking into an eye piece for star alignment and polar alignment plus a lot more accurate
I use it at 2 sites and it gets me well under an arc minute every time , sometimes down to 15 arc sec
Your tripod must be set up facing True South and as level as you can get it
You have to set your ďHome PositionĒ on the mount head and then ďBalanceĒ your telescope before you start your polar alignment
I can send you info on all the above if you wish
Cheers
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Old 06-07-2019, 10:29 PM
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I see, I just tried that an hour ago. I very roughly did the Polar Alignment and did a 3-star alignment with SynScan. At the end of that process the message was Alignment successful, and no error as such. Does that my initial polar alignment happened to be accurate? I find that hard to believe, it was very approximate.

I use ZWO ASI224MC with Sharpcap. I believe the paid version of Sharpcap helps you do polar alignment too. How does an imaging software help you improve PA anyway?

Thanks for the advice by the way.
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  #7  
Old 06-07-2019, 11:07 PM
Startrek (Martin)
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Sounds like you just did a 3 star alignment not a polar alignment
After you complete a star alignment ( 2 star alignment is adequate use Alpha Centauri and Hadar which are close to the south meridian but must be on the same side of the meridian) it will say alignment successful then go to alignment then hit Polar alignment , it will ask you to select a star from the menu, select Hadar , the mount will slew to near Hadar , then it ask you to centre it using and finishing with the Up and Right buttons, press enter , it will then ask you to adjust the Azimuth bolt to bring the star close to centre of your cross hair again press enter, the star will move away again and it will ask you to centre using the Altitude bolt close to where the previous position was a minute ago
Then you have to do another 2 star alignment on the same stars Alpha Centauri and Hadar and when finished it will give you a read out of your Polar alignment error in degrees , minutes and seconds ( 000, 00, 00 ) You have to keep doing this procedure until you get your error down to say ( 000, 00, 15 ) or 15 arc sec

Both stars have to be on the same side of the meridian for both 2 star alignment and your polar alignment procedures

Iím writing this from memory but I think itís right

Usually takes me 3 or 4 iterations to get down to sub arc minute error

Another tip is to de focus your star into a small donut so you can centre it more accurately. I find I get better results but seeing conditions dictates your accuracy


Cheers
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Old 07-07-2019, 12:33 AM
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Ok that makes perfect sense now, thank you!

Now just need to wait for the next clear night
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Old 07-07-2019, 08:36 AM
Startrek (Martin)
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Glad to help
I think it asks you to adjust the Altitude bolt first then the Azimuth , just follow the procedure in the manual
Make sure you centre and re centre using the Up then the Right button , this minimises backlash
Donít worry if you canít get below and arc minute , it takes practice
When I first started using an illuminated reticle eye piece it was taking me 4 , 5 and up to 8 iterations to get the error , now after nearly 3 years it takes me 2 or 3 iterations, about 10 or 15 minutes using BYEOS on my laptop next to the mount ( photo of my set up in Sydney attached )
Good luck !!
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  #10  
Old 09-07-2019, 11:58 AM
tileys
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I would like to give a shout out for the polar alignment routine in Sharpcap (paid version). I can see the area of the SCP - but only just - above a row of bushes but the polar alignment routine - from the parked position and then as guided by the software gets me an accurate alignment within a few minutes and only moderate fiddling with the EQ knobs - mostly the RA adjustments (left and right) as DEC typically doesn't change much after initial setup. I have to setup my EQ6 each session so once I got a good alignment initially I marked on my pavers where each of the tripod feet were with a permanent marker so I get setup the mount and tripod in the same spot each time and always now get a fairly accurate starting point for running the PA routine.

To get the initial bearing on the SCP I made up a template from a laminating pouch (clear stiff plastic sleeve) with little white correction fluid blobs for the pointers and Southern Cross (while the sheet was being held up at arms length facing the stars in question) and then afterwards drew the line down between the perpendicular from the pointers and the Southern Cross so the 2 lines converged about 4.5 times the height of the Southern Cross - that way I can just hold up the sheet at arms length - line up the white dots with the stars and instantly see where the lines coverge (to be honest - the lines converge slightly off an A4 page ).
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Old 22-07-2019, 09:50 PM
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Quote:
Originally Posted by Startrek View Post
Glad to help
I think it asks you to adjust the Altitude bolt first then the Azimuth , just follow the procedure in the manual
Make sure you centre and re centre using the Up then the Right button , this minimises backlash
Sorry to bother you again, but I found that my SynScan controller doesn't give me an alignment error after a successful 2-star alignment, and furthermore the only 3 options I always have under the Alignment menu (before or after a successful alignment) are 1-star, 2-star and 3-star alignments only.

The firmware version of the controller is only 3.10. Does it need to be updated to get those options? The Skywatcher SynScan manuals don't seem to be helpful in relaying if the Polar Alignment option is available for version 3.10. Thanks again for your help!
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  #12  
Old 22-07-2019, 10:10 PM
Startrek (Martin)
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That version must be very old as my mount is 3 years old and the Synscan version is 4.37.03
Sounds like the polar alignment feature wasnít available in the older versions ?

Update if you can and then see if itís in Set up > Alignment > 2 Star Alignment > Polar Alignment
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  #13  
Old 22-07-2019, 10:27 PM
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Just confirmed that the feature was only introduced in 3.39 - http://skywatcher.com/download/softw...ller-firmware/

Quote:
This new SynScan Hand Controller firmware release is an update from the previous SynScan Firmware Version 03.39.03. What's new in this update? 1. Update and correct the Solar Tracking speed in the Solar Track Mode. The Solar Track Mode is a new fuction to track the Sun and does not need an alignment. 2. To use this Solar Track Mode function: 1) Polar align the equatorial mount or level the base of the Alt-Az mount. 2) Finish the initialization on SynScan. No alignment is needed. 3) Activate "Solar Track Mode." Now the mount will start working at solar tracking speed until exiting the "Solar Track Mode". 4) Center the Sun in FOV with SynScan hand controller. 5) Start observing. Warning: Your telescope must be capable of observing the Sun safely. 3. Fix minor bugs.
Good, so atleast I know what my next step is!
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  #14  
Old 23-07-2019, 07:44 AM
Startrek (Martin)
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Attached is a page out of my version 4 manual on how to polar align using the Synscan polar align routine
I perform a 2 star alignment after each iteration ( no need to do a 3 star alignment )
I use alignment stars near the south meridian within 30 degrees on one side of the south meridian near the SCP
Eg Acrux and Hadar
And then use either Acrux or Hadar as my polar alignment star
You donít have to specifically use Acrux and Hadar as long as you find stars to use on one side the south meridian and say 40deg to 60 deg up in Alt
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Old 23-07-2019, 01:02 PM
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Nice! Cheers for that
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Old 23-07-2019, 06:32 PM
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Bluknghtv (Daniel)
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I use sharpcap pro and do a polar alignment using plate solving. Works every time just point the mount in the general direction of the scp then do the RA and Alt Az
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