Automatic mount alignment

[Cepheus0815]

Dear SharpCap team,

I polar alignment my EQ6-R mount with the guidscope and later with your awesome polar alignment routine. After that I manually moved around the sky and aligned stars to get my mount aligned with the sky. Latley I figured out, how to do that far quicker with plate solving, but it is still a manual process to go around the sky, do platesolving and sync it to the mount.

My feature idea would be an automatic sky alignment procedure. Like after you are sure you did a good polar alignment, this procedure should go for all 4 quadrants of the sky (lets say at 45° height) and do a plate solving (incl. sync to mount). You could even enhance it with the following parameters: in which height do you want to do a sync (could even be list to do more per quadrant)?

Does that make sense to you?

Thanks, Rainer

[chongo228]

I don't think I understand....if you can plate solve you're able to align with one button.

I polar align, slew to target, and plate solve. Then the mount syncs and everything is spot on....I'm not sure why you would need to slew to all four quadrants of the sky.

In your first paragraph you say that you are able to use the polar alignment tool. Is your idea to use plate solving to polar align if you can't see Polaris?

[Jean-Francois]

Hello Rainer,

You can read this topic ...
viewtopic.php?f=14&t=2331

I start programming and modifying the scripts from Norman.
At the moment, I receive no answer from Norman.
In the mean time, I concentrate me on the programming of the GPS-LED function of the QHY-174-GPS camera.

I do not forget the polar alignment ... because I have no view to the north from my location.
I have an EQ8 ... the Synscan function of polar alignment after the 2 or 3 stars alignment is not bad, but sometimes several arcminutes away.
If I mount the telescope with the camera fixed, I do not want dismount the camera for a visual polar alignment.
The idea is to use directly the main camera for the polar alignment after the coarse polar alignment done with the finder.


For a general understanding ... some times different things are confused.
- polar alignment => that is the angle alignment of the RA axis of the mount parallel to the earth axis
- pointing reference or GOTO initialization (2 or 3 stars alignment) is sometime confused with the polar alignment
- in addition ... the next level is a "pointing model"

For example ... a telescope (equatorial mount) can have a bad polar alignment (=> 1 deg from the pole axis), but with a 2 or 3 stars alignment, the mount can perform acceptable GOTO in the sky. A plate solve after a slew can improve the GOTO capability of the mount.
That is used only for slewing the telescope ... the bad polar alignment will be visible during an imaging session (guiding error and image rotation problems)
A telescope with a focal length of several meters and with a small field of view needs a better correction ... that is the pointing model. For the generation of a pointing model, the plate solving is used intensively. It could be the multi-triangle interpolation calculation from EQMOD or it is the pointing model from the software Prism (https://www.youtube.com/watch?v=g93_w5j9_RI). The result of the pointing model is the understanding of the mechanical deviation of the mount/telescope/camera system (polar alignment, cone error, RA-DEC angle error, flexion, ...)


Regards,
Jean-Francois

[Cepheus0815]

Hi all,

Thanks for your replies. My idea is to create the point model automatically at the beginning of the session, after a good polar alignment is achieved. With it you should be able to GoTo everywhere on the sky and be more or less spot on. But maybe you are right and I just do a PlateSolve after every Goto, thus enhancing the point model during the night.

[Jean-Francois]

Hello,

It depends on your program commanding the mount.
EQ-6R ... I think that you use the EQMOD Ascom drivers/software.
And it depends if you have a fix location, then you can save and retrieve the pointing model from EQMOD.
If you are each time moving ... then yes, you need to repeat a model pointing or as you say ... use the slew/plate-solving/synchronize capabilities of SharpCap and EQMOD.
You need to verify in the EQMOD window that the number of saved reference point is growing after each plate-solve/synchronization.
Verify that SharpCap action is correct after the plate-solving search.

Regards,
Jean-Francois

[admin]

Hi,

I think that it will be possible for you to implement something like this very easily using the new sequencer tool that is built into SharpCap 3.3. This gives you the ability to tell SharpCap to perform a sequence of tasks that you could otherwise perform manually, but is much easier to configure than using the scripting option that Jean-Francois is using (you don't need any real knowledge of programming to use the sequencer).

You could set up and save a sequence which would instruct SharpCap to go to points at 45° altitude at various different azimuth points and then perform a plate solve and synchronise at each of those points. Then all you need to do is run that sequence after you have set up the system.

See this post for more information : viewtopic.php?f=38&t=3109

Robin

[Cepheus0815]

Awesome, thanks for that advice. I will test that!

[danielrivet]

my understanding is that there is a difference between adding a star to the pointing model and doing a sync. I think that you cannot add a star to the pointing model on my Celestron AVX through ASCOM. You can add sync points but they are not added to the pointing model. Am I right. Thanks
Daniel

[admin]

Hi,

not sure about the AVX, but with EQMOD there is a setting that lets you choose between the two modes of adding a point to the pointing model and doing a plain synchronisation.

Cheers, Robin

[danielrivet]

EQMOD is not compatible with the Celestron mounts and CPWI (celestron's ascom interface) does not have an option to accept a "sync" as an addition to the model. EQMOD does it right...

Thanks for the suggestion.

Daniel