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Asiair plate solve

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#1 Jack160219

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Posted 13 June 2021 - 05:44 PM

Hi, 

 I have a 9.25 Celestron SCT  ( fl 2350) with a 6.3 focal reducer. I have entered a calcuted focal length of 1480, but the setup will not plate solve.

 Does anyone know what focal length will work ? Incidentally I’m using an asi 1600 mc. Thanks for any help. Jack.



#2 Endro32

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Posted 13 June 2021 - 05:56 PM

From the ASIAIR user manual:

 

"At present, plate solving supports the image field of view from 0.4

degrees to 33 degrees. If this range is beyond the resolution, it cannot be
resolved."

 

I checked the field of view of your setup using the astronomy.tools field of view calculator, and your images are going to be 0.68 degrees by 0.52 degrees. These two dimensions are technically within the range of what ASIAIR should be able to handle, but it's so close to the edge that you may just be using too narrow of a field of view. That'd be my best guess, but maybe someone else has a different idea.



#3 Dynan

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Posted 13 June 2021 - 06:27 PM

What exposure length are you using? Maybe increase it a bit. If you're already doing this, I got nothin'...



#4 alphatripleplus

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Posted 13 June 2021 - 07:42 PM

Moving from EAA to Astronomy Software & Computers for a better fit.



#5 Jack160219

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Posted 13 June 2021 - 09:40 PM

I’m new to this so what does that translate to in focal length? That’s the only parameter I can enter in the asiair app. Thanks jk.



#6 72Nova

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Posted 13 June 2021 - 10:37 PM

I’ve only had my ASIAIR pro for a short period of time but I had similar issues when I experimented with my 6.3 reducer 

 

Try entering “0” as focal length and the ASIAIR pro will calculate.  Agree with Dylan to try different exposure lengths too



#7 Jack160219

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Posted 14 June 2021 - 12:58 AM

I went out tonight and tried several different focal lengths without success. It failed on Polaris ,sensing some 80 stars but unable to plate solve, I’m at a loss here. I wasn’t even able to polar align with asiair. I’m open to anything, thanks jk



#8 YossiZ

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Posted 14 June 2021 - 04:06 AM

Try leaving the F value at 0. After the first successful plate solve, the app will update the value automatically.

If the plate solve is not successful, try changing the exposure time or pointing at an area in the sky with more/brighter stars visible.
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#9 Jack160219

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Posted 14 June 2021 - 08:56 AM

Did putting in 0 actually work for anyone or just mentioning what has in the manual?



#10 davidparks

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Posted 14 June 2021 - 10:30 AM

Putting in Zero actually works as documented.  It's a great way to measure focal length of your system when you make changes... aka, add a barlow, reducer, flattener, spacers... etc.   Just drop a '0' in focal length and let ASIAIR solve and measure the focal length for you.

 

If you do put a focal length in, ASIAIR will solve and update the focal length with minor variance... although I do not know what the tolerance is.  Outside of tolerance then the solve will fail.   Example:  A 250 value may actually solve and update as 248, but if it's actually 500 it will probably fail. 



#11 Jack160219

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Posted 14 June 2021 - 11:01 AM

Ok, here’s a real newby dumb question. I’m gona try the above suggestions tonight from by back deck, the only problem is I can’t polar align due to big trees. For the purposes of trying the plate solve , does it even matter how the tripod and scope is setup? I just want to see if it can solve. I sent a jpg without any mount info to nova.astrometry.net and they found a solution. So is asiair similar?  Does it just ignore header files on a fits image and look for a compatible file? Thanks jk.



#12 davidparks

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Posted 14 June 2021 - 12:45 PM

I would suggest setting the scope up in the approximate EQ Home/Polar aligned position (even though you can't actually align) and then slewing/GoTo an area of the sky that can be seen.  That should be close enough for ASIAIR to platesolve.  The idea is to have the internal mount coordinates reasonably close to the actual sky you want to test solve... so set that up any way your mount requires.

 

For example, my RST-135 has a 'Home' position that point West at the Horizon, I would set the scope in that approximate location, forego any alignment, and just slew/goto an open area of sky for the test solve.

 

I'm just not sure what ASIAIR tolerance is for solves, or if it can do a 'blind' solve... so just try to have the actual mount coordinates somewhat in the neighborhood of your solve.

 

 

Also, take a Preview image using the same exposure length as your ASIAIR Solve  (In mount/telescope settings), with your Histogram set to Auto(stretch).  Make sure you can see Stars, and they are reasonably focused  (doesn't have to be perfect focus, but they should be solid dots, not donuts)


Edited by davidparks, 14 June 2021 - 12:49 PM.

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