plate solve and sqm 17

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oopfan
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Re: plate solve and sqm 17

#11

Post by oopfan »

Hi Alberto,

I ran your image through nova.astrometry.net. See attachment. You're looking at a star field between Lacerta and Cepheus, not even close to M31.

Did SharpCap successfully plate solve this for you or did it fail?

Brian
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M31_00001resized-NOVA-plate-solve.png
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oopfan
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Re: plate solve and sqm 17

#12

Post by oopfan »

Hi Alberto,

I have good news. I used SharpCap 3.1 to plate solve your image. Here is SharpCap's output:

Solution : RA=22:34:03,Dec=52:38:51N
Field of View : 0.65x0.44 degrees
Time : Sun, 21 Nov 2021 20:55:47 GMT
Orientation : up is 119.0 degrees E of N

That agrees with nova.astrometry.net

I used my standard setting of SIGMA 9. Using that value, 81 stars were detected in the image. I have found that it is best to adjust SIGMA so that the number of stars detected is in the range of 50 to 100. However, I have been able to solve with as few as 20 stars.

You should try to duplicate my findings. No need to connect SC to your telescope. Do what I describe offline:
1. Launch SharpCap.
2. From the menu, click Cameras -> Test Camera 1 (Deep Sky)
3. In the right-hand panel there is a section called "Testing Controls". Open it up.
4. The first item is called "Image". Click the "Browse" button and select your image file.
5. From the menu, click Tools -> Plate Solve.

In the status bar, SC will show its progress. Be sure to write down the number of stars detected. This should happen within the first 20 seconds. If the number of stars is less than 20 or greater than 100, cancel it and adjust the SIGMA.

Like I said I am running SC 3.1. Perhaps Robin changed the layout in SC 4.0. Ask for help if needed.

Brian
zoltrix
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Re: plate solve and sqm 17

#13

Post by zoltrix »

Thanks again Brian

Lacerta and cepheus are in view from my window

I selected Alpheratz as first star:
RA 0h08m23s - West
while HD213957
RA 22h34m00,32s - North West

I carried out the test with the image m31-00001:
with sigma = 30 plate solving works
with the default value sigma = 50 , plate solving does not work

yesterday night I tried sigma 50 and sigma 75

unfortunately tonight it is cloudy I will try again in the next days

cheers
Alberto
zoltrix
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Re: plate solve and sqm 17

#14

Post by zoltrix »

hello

no way , plate solving does not work
I can not even attach an image, the Sharpcap capture folder being empty :o
I just cancelled the images of my previous sessions some nights ago
I tried low and high sigma values

I use the" Northen and Level" method " by synscan for alignment

Does Sharpcap automaticaly know the first and second selected stars from the synscan menu ?
The failure message shows a pair of coordinates which are not the ones of the stars which I have chosen for alignment

can you figure out what I am doing wrong ?
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admin
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Re: plate solve and sqm 17

#15

Post by admin »

Hi,

SharpCap doesn't know anything about the alignment stars used for setting up your mount, but once that alignment is done, SharpCap can read the mount co-ordinates from the ASCOM driver to know where the mount is pointing.

I think we need to see a screenshot showing how the camera image looks in SharpCap when you are trying to plate solve, the contents of the SharpCap log captured after the attempt to check what happened and ideally another captured image (snapshot button) so we can test to see what happens and why.

thanks,

Robin
zoltrix
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Re: plate solve and sqm 17

#16

Post by zoltrix »

Thanks Robin

I will let you have the camera images as soon as the sky is clear, quite seldom in this season :(
If I understood well SharpCap can not be of help for the alignment of an AZ mount

My idea was :
#1 I use the "North and level" method
#2 I select the two stars
#3 the scope slews to the first star but it does not center it , the orientation of the mount being slightly wrong
#4 I make plate solving
#5 I confirm synscan that the first star is centerd
#6 same for the second star

I wonder :

If Sharpcap is not aware of the selected stars wouldn't it be possible to key_in manually their coords ?
I can get these data from stellarium, even altitude and azimut if needed
If Sharpcap knows which stars I am aiming to , Plate solving should work

cheers
Alberto
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Re: plate solve and sqm 17

#17

Post by admin »

Hi Alberto,

I think the problem is that until you have completed the initial alignment process (selecting the two stars, centering them, confirming on the handset, etc), the co-ordinates that SharpCap receives from the mount may not be correct, which could throw off the plate solving process. Normally plate solving is used to properly center a target after the initial alignment is complete, I'm not aware of people using it in the way you are planning.

cheers,

Robin
zoltrix
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Re: plate solve and sqm 17

#18

Post by zoltrix »

Hi Robin

I was told that Celestron mount supplies a CPWI function, assisting in centering the alignment star
In an heavy polluted condition it can be hard to manually center the star even with the help of a finder
as far as I understood the user simply key_in the coords of the alignment stars, he manually slews the scope to the target and finally he plate solve for centering
It should not be that difficult to implement such function ( from the point of view of an hobbyest programmer, of course :) )

bye

Alberto
zoltrix
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Re: plate solve and sqm 17

#19

Post by zoltrix »

Hi

as soon as the sky is clear I will try something like that :

I do north level alignment
I confirm even though the stars are not exactly centered
Sharpcap should assume that the mount is aligned
I select a star in the nearby from Stellarium
the scope slews to the star, the error should be less than 15 degrees
I plate solve for centering
I repeat the alignment procedure with the "one star " method ", choosing the previous star as target
Just a few seconds later the star should be still centerd
I confirm

Does it work ?

Cheers
Alberto
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Re: plate solve and sqm 17

#20

Post by admin »

Good luck with the test - I would be interested to hear the results. Hope it works!

Robin
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