SharpCap Plate Solving/Celestron Evolution and Sky Safari

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donstim
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SharpCap Plate Solving/Celestron Evolution and Sky Safari

Post by donstim » Fri May 17, 2019 5:22 am

Hi,

I use Sky Safari 6 connected to my Celestron Evolution mount via WiFi for alignment and gotos. This has the unfortunate consequence that the mount does not have the correct position of where it is pointing for any given goto. Since SharpCap Pro uses the mount's position data via a USB cable connected to the Evolution mount's hand controller (and the Celestron ASCOM driver), it is not using the correct position data for plate solving. At least, that is how I understand the issue.

I am trying to see if there is a way to get the Sky Safari goto position data into the mount in some fashion, but could SharpCap be modified to allow a manual input of the mount's position for use in beginning the plate solving process? (Would that work?) SharpCap could then move the mount through the ASCOM driver, but I am not sure if it should try to also sync the mount -- I would be afraid that a big correction might create issues with the mount.

Thanks,
Don

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Re: SharpCap Plate Solving/Celestron Evolution and Sky Safari

Post by BlackWikkett » Fri May 17, 2019 4:21 pm

Check epoch settings in the mount and Sky Safari. This needs to be same for both. Example if your mount is J2000 then Sky Safari needs to use J2000.

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Re: SharpCap Plate Solving/Celestron Evolution and Sky Safari

Post by admin » Fri May 17, 2019 5:20 pm

Hi,

Just trying to check to see if I understand this correctly – you are using both the Ascom driver and sky safari to connect the mount. If you move the mount using sky safari then the Ascom driver doesn't update its internal data with the new mount position, so when SharpCap asks it for the mount coordinates, the Ascom driver gives the wrong answer.

If that's the case then Celestron seem to have a pretty big hole in the design of their sky safari/Ascom software unfortunately. You could of course use the blind plate solving option in SharpCap at any time to find out where the telescope is pointing, but that does not trigger a resynchronisation of the Ascom driver.

Cheers, Robin

donstim
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Re: SharpCap Plate Solving/Celestron Evolution and Sky Safari

Post by donstim » Fri May 17, 2019 8:06 pm

Hi Robin,

Yes, that's pretty much the way I understand it. I am using SkySafari via Celestron Wifi to connect to the mount for alignment and gotos. This does not use the ASCOM driver and the alignment information is kept entirely within SkySafari. (I think it computes and stores an offset from the mount's reported position, but that offset is not sent back to the mount for syncing.) So when I connect SharpCap to the mount via the ASCOM driver, the mount gives the wrong answer. I agree that this seems like a pretty big hole in the Celestron/SkySafari integration (and don't know the reason for it), but they seemed to have done it intentionally as there are plenty of warnings to align the telescope using the hand controller OR SkySafari, but not both as it can cause a tussle between who's in control.

I thought about the blind plate solving option, but that would probably take longer than just manually centering the object of interest (unless the object was not in view at all). With blind plate solving, does it give you a position that I could then manually enter into SkySafari?

What I was envisioning as a potential workaround (for me, but would be more work for you and probably not worth your time if it isn't a feature desired by a lot of other SharpCap Pro users) is sort of a semi-blind plate solving. In this case, instead of completely blind plate solving, you would tell SharpCap to tell the plate solver the object you are intending to center in the FOV. That would limit the area of the sky that the plate solver would need to check against. Then I don't know whether it would be possible for SharpCap to move the telescope to center the object using the ASCOM driver or provide information that the user could use to do that.

I think I will check with Celestron to see if there is any way forward for filling the "hole" they have in their SkySafari WiFi integration with their mount.

Thanks again,
Don

celkins
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Re: SharpCap Plate Solving/Celestron Evolution and Sky Safari

Post by celkins » Sun May 19, 2019 12:58 am

Don,
you seem to be missing the point that SkySafari isn’t a Celestron product - it’s from Simulation Curriculum... Celestron licence a simple version of this for “plug & play” users.
The reason for the warning to use either hand control OR SkySafari is because only one of them can control the sky model... it’s either entirely in the handset, or it’s in SkySafari, and you make this choice when you align the mount.

I use SkySafari for object selection, but via the ASCOM driver, so that I can use PHD to guide on my targets; I link SkySafari to the ASCOM driver via WiFi Scope (a free download from Main Sequence Software) after using the handset for alignment.

donstim
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Re: SharpCap Plate Solving/Celestron Evolution and Sky Safari

Post by donstim » Mon May 20, 2019 1:15 am

Please don't distract the discussion from what I am seeking. I am specifically seeking a way to use SharpCap's plate solving without using the handset for alignment. The SkySafari WiFi alignment is quicker, easier, and more accurate.

I may switch from SkySafari to Celestron's new CPWI software, but I suspect I will run into the same issue regarding using SharpCap's plate solving capability.

Robin, another pie-in-the-sky idea I had would be if there was some way to have SharpCap center a mouse-clicked point anywhere in the current field of view. But I guess there is no easy way for it to "calibrate" what movement it would take to do that.

Don

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Re: SharpCap Plate Solving/Celestron Evolution and Sky Safari

Post by admin » Mon May 20, 2019 9:56 pm

Hi Don,

In theory, once you have done a plate solve of a field-of-view, you can calculate not only the position of the centre of the field of view but also of any arbitrary point within it. Therefore you could calculate the RA and DEC of the point that is clicked on and issue go to to the mount to centre that point in the field of view. That's a feature that's been discussed elsewhere is certainly something I would consider in a future version. Of course in order for this to work, you need the plates solving to work which in turn relies on the Ascom driver providing good information to SharpCap.

I assume that the Celestron Ascom driver is not expecting the telescope to be issued with commands from any other source, so it has no idea that it needs to re-query the position of the telescope periodically to maintain correct data. I think if you found a solution that used software exclusively running on the PC, you may find that everything works as expected, as all commands to the telescope would be sent via the virtual handset and the Ascom driver.

Cheers, Robin

donstim
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Re: SharpCap Plate Solving/Celestron Evolution and Sky Safari

Post by donstim » Mon May 20, 2019 11:22 pm

Hi Robin,

The new Celestron PWI (CPWI) telescope control software appears to be the PC-based program that will get this to work, and it can all be done wirelessly. The CPWI program has its own mount driver that appears to talk to the Celestron ASCOM driver (at least, that is how I understand it). Anyway, however it works, I can connect to the telescope and do the alignment with CPWI over WiFi. Then I can connect SharpCap to the CPWI mount for plate solving. I can also use SkySafari for GoTos by using WiFI Scope also connected to the CPWI driver. (Thank you celkins) for letting me know about WiFi Scope!)

I don't need any physical connection with the hand controller nor do I need to do the alignment with the hand controller.

Thanks all,
Don

P.S. It would still be neat to see the point-and-click to center an object capability. Better than bringing up the reticule and trying to do it manually.

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