One of Jasem's videos suggests that when you start out to set your FOV to 0' x 0' and let the software figure out your exact FOV. Reasoning is, although it takes longer for the first run, there are so many variables that can change the FOV even by a little. Thanks for posting this thread, I've had similar thoughts. I've got a pier and I rarely have to adjust my PA, but even a tiny correction can make a big improvement in guiding.
Part 9: Ekos Alignment Module

I have watched that video. The FOV figure I am using is the one that was returned by ‘Load and Slew’ process so it looks like it is pretty accurate.
In my case I set up the mount anew each evening, so performing a reasonably speedy and accurate PA is crucial. I do have a fresh software installation to test out, on the next clear night.......

I have not tried the PA tool, but really want to. I was under the opinion that it requires an open view of the sky. I have a fairly narrow view between trees and the house... oh well.

What I've been using the app "PS Align Pro" on my phone and my Skywatcher EQ6-Pro mount seems to do a really great job, but I would like to really nail the PA with the the EKOS module.

Oh and I understand your "next clear night"... it's been terrible here in Maryland.

I don’t have a polarscope on my mount, and I am still hopeful that I may not need to buy one! The FOV of my scope is a little over two degrees which I suspect would still be rather narrow in terms of the gap between ‘the trees and the house’ in your situation.
I am hopeful that an earlier posting about using Jpeg rather than RAW images may have some significance.......

Like I wrote, for us changing to JPEG at least made the polar alignment routine work. And I think using JPEG for slewing also should work. However, this is a temporary workaround until it is clear what's wrong. I have used CR2 RAW files (converted automatically to FITS by Ekos) for polar alignment and slewing LOTS of times and it always used to work. Meanwhile just don't forget to set it back to RAW when you actually start imaging because we forgot to do that...

We are trying to solve some of the FITS files on the command line on Linux and the solve-field command times out all the time. Next I hooked up the DSLR camera to my MacBook and tried the solver again. The solver completes in 5 seconds. In the Image Settings tab of GPhoto CCD in the INDI Control Panel, both on Linux and Mac Image is set to RAW and Capture Format is set to RAW. Only when we set it to one of the JPEG formats on Linux, the solver will succeed and it succeeds within a few seconds.

Did anything change in the RAW to FITS conversion in KStars recently?

I cannot upload any FITS files here and even renaming them to .txt won't work because they are too big. One of the FITS images that fails under Linux can be downloaded here

quasar.van.reeven.nl/fitsbe6740.fits

The files resolves fine on Mac when going to the Align tab and choose "Load and Slew".

OK I managed to solve the fits image but I do not understand why! Looking into the KStars logs of last night, I see that this command line was used

/usr/bin/solve-field -O --no-plots --no-verify --resort --downsample 10 -L 166.25 -H 275.1 -u aw -3 3.82196 -4 90 -5 20 --config /home/wouter/.local/share/kstars/astrometry/astrometry.cfg -W /tmp/solution.wcs /tmp/fitsbe6740.fits

and then the solver times out. Using the Load & Slew functionality in the Align tab of Ekos, which succeeds both on Mac and Linux, I was able to compare the command line options and I found that the solver succeeds if I remove the -L and -H command line options. In other words, this works:

/usr/bin/solve-field -O --no-plots --no-verify --resort --downsample 10 -u aw -3 3.82196 -4 90 -5 20 --config /home/wouter/.local/share/kstars/astrometry/astrometry.cfg -W /tmp/solution.wcs /tmp/fitsbe6740.fits

So, the basic question is: Why does it not work with the -L and -H options but it does work without?

The solution seems simple enough: in the Align tab Solver Options (either click the pencil icon behind the Options text field in the lower left of the Align tab screen or click the Options button to the lower right in the same screen) untick the Use Scale option in the Imaging Options section. I am not sure if I can test this tonight since the weather forecast is not very good but let's see. I'll be traveling on Friday but perhaps I can test this on Saturday or one of the days after.

Avocette, please try this workaround and post your findings here. Perhaps you are able to test this before I am.


Wouter

The weather was favorable and we were able to test this. Indeed, disabling the Use Scale option solved the issue for us.



Wouter

Hi wvreeven - it's morning now and I will look into this question soon. However I have better news from last night's experiences - Polar Alignment worked for me!
I'm trying to unpick the sequence of events that took place which led up to this success.
Firstly I tried out a fresh installation of Raspian/Kstars etc that I compiled in the last few days. After initialization with my equipment specific parameters I tried a Polar Alignment. After the image capture, the solver began and 'failed' immediately. The commentary suggested 'try again'. I stopped the present PA and started it again with identical results. I then tried capturing an image and hit 'Load & Solve' but could not find any saved image to solve. I subsequently located images with the suffix .fits.fz which were not recognised in the Load & Solve file window.
So I switched over to my old SD card last used on Sunday night. In the meantime I had a spontaneous realisation that I had been using the effective focal length of the combination of my 80mm x 600mm scope with FR/FF as 540mm rather than the correct 480mm. So I changed the telescope specification in Ekos to this value, and perhaps that sorted something out? I will now run up my RPi and look in detail at the present working contents of Ekos/Indi fields. I'll also look into whether the Use Scale box happens to be ticked or not.

Hi Avocette,

Yes the focal length of the telescope is crucial for plate solving so that indeed probably fixed your issue. I am glad that we both got to solve our plate solving issues!


Clear skies, Wouter

Second night of opportunity to test out Polar Alignment in clear sky, this time with a fresh installation of KStars/Ekos/Indi using the very latest available (cloned 31/8/2019) AstroPi3 script for the RPi4 and Raspbian Buster. I’m a happy man - the PA routine solved each image in 10 seconds! Admittedly unfortunately the clouds then rolled in before I could tackle the 2° 02’ alignment error.
Thanks to all for your encouragement!