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INDI Library v2.0.6 is Released (02 Feb 2024)

Bi-monthly release with minor bug fixes and improvements

Alignment and plate solving w guide scope problem

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Hi!

This is of course a problem on my way to try and use the new PAA, but it's not directly related to that so I post as separate topic.

When trying to use my guide scope in the aligment module, two things happen. When I switch to it, the FOV gets filled in with a quite small number (like 17 x 14', or similar - don't have it connected right now). But the FOV of the guidescope should be more like 45 x 35'. So where does these fgures filled in the FOV come from? And I cannot change them. And I cannot see where in the Indi control panel they would come from.....?

Secondly, and possibly related to this: the solving consistently fails. I use exposure times of 0.5 secs or 1 sec, there seens to be no gain control on it (a Lodestar). Is there anything I can tweak to be able to solve it? When saving an image and uploading to nova.astrometry.net, it solves (after a while).

Magnus
7 years 1 month ago #14714

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Check your mount's INDI options tab. You will find there your telescope's and guider's aperture and focal length. Just set it up and you should be fine.
7 years 1 month ago #14718

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Yeah, well, it is set: 500 mm focal length and 70 mm aperture. But how does INDI make that into some 17' FOV? No other settings I should check?

Magnus
7 years 1 month ago #14719

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INDI uses these plus your CCD camera settings - pixel size and resolution. Check these out
7 years 1 month ago #14720

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Hi!
Yes, I seem to have the correct pixel size and resolution in the Indi panel: sensor is 752 x 580, pixel size 8,2 x 8,4 microns.

The aligment tab shows a FOV of 17 x 12 arc minutes, see the attached screenshot. But: I can solve an image on nova.astrometry.net, and that gives me a FOV of 43.3 x 33.4 arcmin. The image I solved there is attached too.
And: I cannot solve this imate with the offline solver in Ekos. I do Load & slew, and a blind solving, but it aborts after 180 seconds. Can you solve it?

Edit: the solved image on nova.astrometry.net: nova.astrometry.net/user_images/1516929#annotated

Magnus
Last edit: 7 years 1 month ago by Magnus Larsson.
7 years 1 month ago #14799
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I can solve your image with offline solved without problem.
Please note the fact that you set binning to 2, which changes your FOV. It seems that FOV numbers you're referring to are valid for binning 1 and for binning 2 the ones displayed in EKOS are probably right. EKOS uses only telescope/guider focal lenght from telescope options tab, pixel size and CCD resolution from CCD driver. These are the only parameters needed to calculate FOV. Take a look at useful formulas and calculate your arc-sec/pixel first and multiply the number by CCD resolution to get FOV in seconds (divide by 60 to get minutes).
7 years 1 month ago #14820

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Binning does not change the FOV, it changes the pixel scale of the image (arcsecs per pixel). What's your focal length? It's suppose to be around 1000mm.
7 years 1 month ago #14827

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Yeah, I was not precise saying this. FOV depends on focal length and physical size of CCD chip.
As stated above his focal length is 500mm.
7 years 1 month ago #14829

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Hi!

OK, so binning might be playing with me here. I normally have binning 1 x 1, have no idea where and why it suddenly should be something else, but I'll check next time it's connected (then the clouds part and I set it all up).
If FOV is something around 43 x 33 with binning 1 x 1, should it not be a clear fraction of this with binning 2 x 2, that is, 21,5 x 16,5? The 17,2 x 12,8 sounds odd, doesn't it? Or there are other things in play here, producing those numbers?

And: when you solve the image, what are your parameters? I just can't make it solve.

Magnus
7 years 1 month ago #14833

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I have used default settings for plate solving with EKOS and loaded the image with Load and Slew using offline solver.
Astrometry was down recently (it is up now) so you might have had some problems while using online mode.
7 years 1 month ago #14835

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Hrm. Odd. I use default settings, and tje jpg-file I posted here, and it aborts after 180 secs. Du you know which index is used to solve it? (maybe I don't have the correct ones)

Magnus
7 years 1 month ago #14836

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Here you go
2017-02-26T22:53:11 Solution coordinates: RA (21h 34m 02s) DEC ( 60° 07' 38")
2017-02-26T22:53:11 Solver RA (323.39) DEC (60.05) Orientation (-168.86) Pixel Scale (207.5)
2017-02-26T22:53:11 Solver completed in 136 seconds.
2017-02-26T22:53:11 
2017-02-26T22:53:11 Field center: (RA,Dec) = (323.393589, 60.050349) deg.
Field center: (RA H:M:S, Dec D:M:S) = (21:33:34.461, +60:03:01.257).
Field size: 43.4002 x 32.0812 degrees
Field rotation angle: up is -152.623 degrees E of N
2017-02-26T22:53:11 Field 1: solved with index index-4219.fits.
7 years 1 month ago #14837

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