Newbie-Plate Solving Problem ASTAP

Discussion of using SharpCap for Deep Sky Imaging
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erdoc
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Joined: Fri Nov 13, 2020 7:29 am

Newbie-Plate Solving Problem ASTAP

#1

Post by erdoc »

Trying to see if I can try out plate solving at home before I spend two hours traveling out to my semi-dark site using my Atik Infinity camera.

I can successfully control my Evolution mount with CPWI via SharpCap, and would like to see if plate solving works.

To that end, have selected as camera the deepsky camera simulator, which brings up the Orion nebula and neighborhood.

When I click on TOOLS, then PLATESOLVE (Yes, I know it won't move or center the mount),Astap pops up, program runs for about a minute, I get a "No Stars Found" error. Tried fiddling with the gain, no help.

Do I need to do a Capture or some other action for it to do the plate solve, or does it not work with the simulated camera?

Does the mount need to be connected for the TOOLS platesolving to work? I connected my mount last night, fake aligned it so it thought it was pointing at Rigel on CPWI, tried the synch and center plate solve, and SharpCap still said no stars.

If no mount is hooked up, does it perform a blind solve, or does it need the mount connected to know where to begin its search?

Thanks,

Robert
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Re: Newbie-Plate Solving Problem ASTAP

#2

Post by admin »

Hi Robert,

the easy bits first... The 'Plate Solve' menu option does a blind plate solve and takes no action with the results other than to display them in the notification bar.

In SharpCap 3.2 this solve is truly blind - ie it starts from RA=0, Dec=0 and scans the whole sky. In SharpCap 4.0 if you happen to have an ASCOM mount connected then it will use the current co-ordinates from the mount as a hint - it will start from the mount co-ordinates and then scan out over the whole sky. The final outcome will be the same, but if it does work it is likely to work faster in 4.0.

Now, as to why Astap is not detecting any stars, I wonder if that might be an incorrect error message? I've sometimes seen that come up for other failures - certainly when I try with Astap with the sample orion image it works nicely.

My suspicion is that Astap works best when it knows the field of view - if that isn't set then the search may fail. If you use the plate solving button in the mount controls then it will try Astap twice - once with the currently remembered FOV and again with a command to try a variety of FOV sizes - that usually works. For the blind solve from the menu it may give up before trying all possible fields of view.

The fix for this is to either try from the mount controls (with the mount 'pretend' moved to M42) or to adjust the FOV in Astap. If you run Astap, click 'Stack' and then look in the 'Alignment' tab, you can set 'Field of View (height)'. For the Sample M42 image this should be 1.14 - it will obviously be different once you move on to real imaging.

cheers,

Robin
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