Plate Solve Problem

[rac19]

When I last used Plate Solving, a few months ago, it worked well but that no longer seems to be the case.

The image below shows the results from "Test Selected Plate Solver" in Sharpcap Settings. In the brown bar at the top of the image the CPWI coordinates can been seen and they are plainly quite different. The test button finds 32 sources whereas "Plate Solve and Resync" finds 994 sources.

Does the test button use a in image from the camera? If so why is the result so different to a Plate Solve and Resync?

[rac19]

I should mention that the problem persists even when there are no errors regarding the sigma setting, exposure etc.

Something that has changed since I last used plate solving successfully is daylight saving. The computer is defiant on DST though.

[admin]

Hi,

the 'test' button sends a known image (C:\Program Files (x86)\SharpCap 4.0\SampleFiles\vert_0001.png) to the plate solving engine - this is a 1280x960 starfield taken near the north celestial pole. It tests whether the plate solving application works properly, but can't necessarily tell you whether the sigma value and other settings you have chosen in SharpCap are correct, since it will not really match your camera in terms of star brightness, noise level, etc.

Since you are getting such a large number of stars detected, I'd suggest either increasing your sigma value (15 is low - try turning it up to 50 or so), or turning on the 'send 8 bit images to the plate solving application' option. The later will eliminate low level noise that might be in high bit depth images, this noise can sometimes get mistaken for stars at low sigma.

cheers,

Robin

[rac19]

Latest update. I stopped everything, rebooted the computer and started all over again and now it solves almost instantly. A wasted evening but I am happy that I didn't make things worse by removing, reinstalling etc. I suspect that Ansvr was in a funk.

The test button still returns a different solution (the same values), so that was irrelevant.

[rac19]

The problem came back tonight.

I wonder if it was due the fact that Sharpcap was connected to the scope via CPWI and I used Sellarium (also connected via CPWI) for GoTo.

When I restarted everything and used CPWI for GoTo, not starting Stellarium at all, it worked perfectly.

The question might be, from where does Sharpcap read the most recent GoTo coordinates? Does it read them from the mount or CPWI? If the latter, using Stellarium for GoTo might mean that it doesn't read the correct information.

[admin]

Hi,

SharpCap gets the co-ordinates from the selected ASCOM mount (CPWI in your case). It re-reads them every couple of seconds. You should be able to see this in action - connect everything up and then move the mount (say from Stellarium) - you should be able to see the co-ordinates update in SharpCap. Similarly if you move the mount in SharpCap then Stellarium should show the mount position updating. If this is not happening then something is going wrong.

cheers,

Robin

[rac19]

Thanks Robin, so plate solve reads the coordinates as displayed in Sharpcap as read from CPWI, correct? I have assumed, until now, that it was the most recent GoTo target coordinates.

Last night I connected CPWI to the 'scope and both Sharpcap and Stellarium to CPWI. It seemed to me that plate solving worked (quite quickly) when I issued GoTo from CPWI but failed when I initiated GoTo from Stellarium. There was no problem with Stellarium being connected, it was only when I initiated a GoTo from Stellarium that there was a problem.

Now that I have a clearer idea of how it works, I will experiment further next time. If I arrange my windows so that the coordinates for CPWI and Sharpcap are in view, they should be identical, I would think. If I have the same problem with Stellarium GoTo, I will post a screenshot showing these two sets of coordinates and the coordinates reported in the error.

I prefer Stellarium over CPWI for planetarium features and GoTo. I find the object search to be more flexible, the sky visualisation to be superior and I have a custom landscape to show me where the trees and other obstructions are.

[admin]

Hi,

yes, you should see the same co-ordinates in both (at least to within a small error as they might update at slightly different rates).

I must admit that I haven't used CPWI (my Celestron mount is too old), but this sort of thing should work nicely. I personally prefer SkyTechX as a planetarium app (not as clunky as Cartes du Ciel, but slightly less 'nice graphics' oriented than Stellarium). Having both SkyTechX and SharpCap talk to EQMOD is no problem.

Out of interest, have you tried using the ASCOM 'Device Hub Telescope' from both SharpCap and Stellarium - you set both up to talk to that and then set the device hub telescope up to talk to CPWI. As far as CPWI knows it is only receiving commands from one source, which might work around your problem.

cheers,

Robin

[rac19]

Hi Robin,

When clear skies return (not tonight unfortunately), I will start CPWI connect it to the scope the connect both Sharpcap and Stellarium to CPWI.

CPWI is supposed to act as a telescope hub too (for compatible Celestron mounts only) and it seems to work so far as issuing GoTo commands is concerned.

I will start by issuing GoTo commands from CPWI few times and test plate solving. I expect it to work reliably and solve quickly. I will then issue a GoTo from Stellarium and see if the breaks plate solving.

I am wondering if Sharpcap might stop getting coordinate updates after a GoTo is sent from Stellarium. The both get updates initially, that's for sure and Stellarium continues to get updates after a CPWI GoTo. I don't normally use Sharpcap for manual slewing, by the way. I use the always on top CPWI slew window.

Does Sharpcap poll CPWI each time for coordinates or does it subscribe to CPWI for periodic updates?

[roelb]

I use both CPWI and Stellarium at the same time without any problems. You can even connect simultaneously with several planetarium programs.