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Exos-2gt pmc8 mount alignment


Kevin Rea <reakevinscott@...>
 
Edited

Hi guys,
I am coming from a Celestron 4SE, so I'm used to getting it aligned before I can go and Chase planets.
But now I have Celestron C8 mounted on my new exos-2gt mount.
So am I to understand that before I go chasing objects, I should do the polar alignment, and then a two or three star alignment?
Is this the correct procedure before I go photographing objects?
When using the 4SE, the handheld computer remote,  it takes you first to polar alignment, and once you have done that you press the button and it takes you to the two or three star alignment.
Then as you go through each step you press the button and it takes to The next step until you are finally completed and it says successful.
On Howthe new EXOS-2 GT mount,  do you know that each step is successful?

Thanks,
Kevin Rea
Lancaster, California USA


Wes Mcdonald
 

Kevin

Oh boy.

If you want to do serious astro you are going to want to go serial ascom.  But if you want to use  explorestars:
1.  You should polar align.  This will help with star drift as the explorestars alignment is virtual only not physical

2.  You should read and execute my procedure posted in the files section of either mounts or main that describes how to find polar home.  Do this.

3.  Set the scope to polar home after polar aligning and start everything.

4.  Now just goto  a star and perform a sync.  At that point the go-to accuracy should be pretty good.  

5.  Now go-to and make sure the explorestars mode is "T"

But I must warn you that unless you guide with that C8 focal length you are going to have some lousy stars, as the PE is in the order of 15 arc seconds ok to pk.

You could also go ahead and refine your go-to by doing a virtual alignment after a physical.

More as questions arise.

Wes

--
Wes, Southport NC
PMC-8, ES ED 127, 10" LX200GPS, Astro-Tech 8" Newt, ETX-90
Polemaster, Orion ST-80 and SAG
Electrical Engineer, Retired


Daryl Larkin
 

I don’t think it’s necessary. When I image planets, I point my telescope’s alignment roughly north but that’s it.  I don’t polar align or use GoTo since planets are obvious and easy to find. Because you’ll be shooting many images at short exposures, if the planet drifts a little, it’s not a problem. 


Wes Mcdonald
 

Kevin

The 2-3 star alignment routine steps you through each star.   The best way to see if it worked is to go to settings and enable show alignment.  The alignment coefficients are displayed on the main page.  These should be near about 1 and 0.  If the numbers are huge then the alignment is bogus.  It might be bogus if they are more or less correct but definitely bogus if way out.  Another indication of bogus alignment is NaN listed as telescope position.  

Btw for planets for sure just do a 2 star.  It's easier and plenty good enough for planets I believe.

Wes

--
Wes, Southport NC
PMC-8, ES ED 127, 10" LX200GPS, Astro-Tech 8" Newt, ETX-90
Polemaster, Orion ST-80 and SAG
Electrical Engineer, Retired


Kevin Rea <reakevinscott@...>
 
Edited

Hi Wes,
When you say serial ascom, am I correct in assuming that instead of using the wireless mode to connect from the pmc-8,  to use a serial cable directly from the PMC - 8? If so, that is what I am already doing. I run it from the serial connector on the PMC - 8 into the USB powered hub, which then goes to the computer.
By the way, I am also using the 6.3 reducer on the scope.

Kevin


Kevin Rea <reakevinscott@...>
 

Actually I'm going to be doing more deep space objects than planets. So I need a really good alignment.
Kevin


Kevin Rea <reakevinscott@...>
 

Hi Wes, I wasn't really going to use explorer stars for my alignment or anything else.
I was hoping I could use Astro photography tools software.
Kevin


Kevin Rea <reakevinscott@...>
 
Edited

By the way guys this is the stuff that I purchased to upgrade my Mount and everything to go with it.

This mount, https://www.highpointscientific.com/explore-scientific-exos-2gt-goto-equatorial-mount-with-pmc-8-electronics-exos2gtpmct3-00
 
This autofocuser,
https://www.highpointscientific.com/celestron-focus-motor-for-sct-and-edgehd-94155-a
 
This camera as a guide camera,
https://www.highpointscientific.com/zwo-asi120mm-mini-monochrome-astronomy-camera-asi120mini
 
This Celestron off-axis guider,
https://www.highpointscientific.com/celestron-off-axis-guider-93648

And this to replace the DSLR I have been using..
https://www.highpointscientific.com/zwo-asi290mc-usb-3-color-cmos-camera-asi290mc


Kevin Rea <reakevinscott@...>
 

Hi Wes,
I could not find any files uploaded by you in the files section of this board..
Maybe you could get me a URL for it?


Wes Mcdonald
 

Kevin:

Ok.  Now I know what you are up to.

1.  I advise you strongly to connect to the PMC-8 via the serial cable, not wifi.  No problems with dropped connections etc.  
2.  You will use the ASCOM platform and the ES Ascom driver for the PMC-8.
3.  APT also will connect to the mount via ASCOM hub.  With APT you will be able to run the mount, the focuser, camera, guide camera I believe.
4.  You will use the PHD2 to guide.  I also connects to the mount via the ES ASCOM driver, using pulse guiding
5.  With an OAG on your scope your ASI 120 should be fine.  You might want to figure your view per pixel and see how this relates to your camera arc secs per pixel.  You can research this on the web but in my view you only need to have guide pixels about 2 or three arc seconds in size which should guide you better than the mount can practically be guided.  But then some Exos-2 mounts can be guided better than others.  Bob Hoskins has posted a paper on how to adjust and tune the backlash and other aspects of the mount that contribute to your ultimate guiding errors.  You can find it in the file section of one of the forum sub-groups.  You might read through it and see what you want to do there.  I don't have an OAG, but with my guide scope and ASI 290MM mini I get about 2.5 arc second pixels and guide between 2 and 1 arc seconds combined RMS.  
6.  For alignment, you will need to use something that gets you physically aligned.  ES does not provide software to do this in ASCOM, but you do have a polar scope on the mount which you can use to align the mount.  IF you don't want to do it that way (I never could) you can add a Polemaster or use Sharpcap with you ASI I believe.  You should look into this, as it is easy to use, inexpensive, and accurate.  I use a polemaster because I already owned one, and it is also a breeze and very accurate -- PHD routinely tells me I am good to a few tenths of an arc sec or better.  Don't know if I believe it or not, but guided images are not disturbed by any polar drift (to the limits of my guiding sessions anyhow)
7.  If you are using APT, you can use the plate solve capability it provides to find your DSO objects, dead center.  It uses Platesolve2 software which you will need to download one time, follow APT manual instruction for this.  APT and Platesolve2 will control the mount beautifully to put objects dead center.  With plate solving, you need not worry about stuff like DEC home error like you do with open-loop gotos in explorestars, for example.  So you don't need my article.
8.  So make sure you polar align.  Then put the mount in its polar home position indicated by the little alignment arrows on the RA and DEC axes.  I colored mine with a silver sharpie to help see the danged things.  Then start the PMC-8, boot ascom, etc.
9  You may want to use a planetarium program such as Stellarium or Cartes Du Ceil (or what ever the danged thing is named).  CdC connects directly through the ASCOM POTH hub to the scope.  Stellarium requires a helper app called StellariumScope.  You can research these and see what you like.  APT at least includes integration with Stellarium that allows you to import target locations from STellarium.  That way you can pick objects graphically in Stellarium, import the object into APT and carry on from there with commanding a slew to the object etc.  All through the POTH Hub which uses the ES ASCOM driver.  It all works pretty well, except for the usual Windows related crashes.

So thats a lot.  Not sure what you have done before in this arena, but you have bought a lot of gear and it sure looks like you will have a nice rig once you get it all up and running.  

I'll send a link to Bob's paper and mine for fun in another note.  I don't trust this editor not to lose my response while I go look for them.

Wes.

--
Wes, Southport NC
PMC-8, ES ED 127, 10" LX200GPS, Astro-Tech 8" Newt, ETX-90
Polemaster, Orion ST-80 and SAG
Electrical Engineer, Retired


Wes Mcdonald
 

Kevin:

Go here:   MOUNTS@ESPMC-Eight.groups.io

And look at the files section.  In it you will see Bob's paper, my paper and a sketchup by Vince for the mount mechanics.  This should help.
Wes.

--
Wes, Southport NC
PMC-8, ES ED 127, 10" LX200GPS, Astro-Tech 8" Newt, ETX-90
Polemaster, Orion ST-80 and SAG
Electrical Engineer, Retired


Kevin Rea <reakevinscott@...>
 

Thank you very much Wes.

Kevin


Kevin Rea <reakevinscott@...>
 

Hi Wes..
I looked everywhere and there is no Bob's files that I can see...


 

Kevin,

It was down in the Files section of Mounts, here:

https://espmc-eight.groups.io/g/MOUNTS/files/EXOS2PMC8_TuningNotes_v1.pdf

--
Mounts: ES PMC-8 EXOS2
Scopes: SV 102EDT, ZWO 60/280 Guide
Cameras:  Nikon D5300, Altair GPCAM2-IMX224C
Software: ASCOM, CdC, AstroTortilla, BYN Pro, Sharpcap, PHD2
Computer:  Thinkpad x230, Win7Pro/64


Kevin Rea <reakevinscott@...>
 

When I click on that URL, it just takes me to the main page.


 

Oh - you may have to join that group first.   Here's the link to Jerry's sticky on that:

https://espmc-eight.groups.io/g/MAIN/topic/please_join_the_syshelp/29766749


--
Mounts: ES PMC-8 EXOS2
Scopes: SV 102EDT, ZWO 60/280 Guide
Cameras:  Nikon D5300, Altair GPCAM2-IMX224C
Software: ASCOM, CdC, AstroTortilla, BYN Pro, Sharpcap, PHD2
Computer:  Thinkpad x230, Win7Pro/64


Kevin Rea <reakevinscott@...>
 

That is what it was, I had to join the group. Now I can download it just fine. Thank you very much.