Plate solving inconsistency - STILL

[Christian Hennes]

Hello Bob,

Although this previous thread was closed, I must reopen it because our plate solving problems have resurfaced...
Please consider the attached log from 2/14 showing the following message repeatedly:
''** The time limit for plate solving has expired.''
Until then we had no more issues, as illustrated in the log of the 2/3 session (as an example).
We did not change any settings in ACP Preferences (see attached image) nor in the Planner.

Please advise.
Thanks a lot, as always.

Christian.

[Eric Dose]

"Time limit" is probably the least useful error message possible for diagnosis: the cause could be your mount, camera, catalog, plate-solver, or even the RA,Dec fed to the plate-solver by MaxIm etc.

So let me pose 4 questions I use to diagnose plate-solving, in order:

1. On visual inspection, is the image any good?
2. On visual inspection, does the image show the sky region you expected?
3. Can you plate-solve the image in MaxIm, using a basic catalog (GSC or ATLAS)?
4. Why are you using the catalog you're using? (I haven't used USNO A2 for many years--ATLAS is far superior, and even GSC should be sufficient for your image field of view).

Good luck with this.

[Bob Denny]

Christian -- I go with Eric's #4 suggestion:

19:18:14 Calculated field of view (arcmin): H = 42.9 V = 28.6

The GSC should be entirely adequate. The USNO A2.0 has become old and stale due to no proper motions. I have updated the article on catalog choice and downloading to downgrade A2.0: Downloading and Using PinPoint Reference Catalogs (Updated Feb 2025)

Try switching to the GSC.

[Christian Hennes]

Hi
Going back to GSC catalog did not fix the issue. Still plate solving failures as shown on the attached log.
Any idea highly appreciated!
Thanks!

[William Bristow]

Hi Christian.

Bob is away until Wednesday, 5th March.

I see in the log that plate solves fail right from the first autofocus run, does your telescope have a very large focus change with temperature?

I found that the first autofocus run of a session would often report plate-solve errors and autofocus failed because the focus point when the telescope ended the last session in the very cold early morning was very different to the focus point when starting the session the next evening in warmer conditions.

For a while I manually focused the telescope at the beginning of the evening session before starting up ACP and FocusMax to ensure the focus was good enough for the first plate-solve and autofocus run, eventually I set up FocusMax to use temperature compensation and now FocusMax always adjusts the focuser according to ambient temperature before plate-solving and beginning the first autofocus run.

The other thing I notice in the log is that ACP (or FocusMax?) is selecting the blue filter for plate-solving during the autofocus run, is that a real necessity or a configuration error?
I’m not sure the blue filter is the best choice for plate-solve and autofocus for an RC optical system and I would have expected luminance, or maybe red, to be the right choice for plate-solving the initial telescope position for autofocusing.

If nothing above is relevant can you provide some sample .fit images from the run that failed to solve, I don’t think there’s much else can be learned from the log alone, also the .fits headers can be checked to see if they have the right pixel size and binning information which PinPoint needs for a successful plate-solve.

William.

[Christian Hennes]

Hello William,

Thank you for chiming in.

The focuser is not very sensitive to temperature change.
As for the filter used for plate solving, I have set it as the "0" (see attached) filter which should be Luminance (please refer to the filter numbering in Maxim attached).
Why would ACP choose the Blue filter for plate solving in such condition?... Really wondering!

Thanks again!

Christian

[William Bristow]

Hi Christian.

If you are using FocusMax Star Selection, see > ACP Preferences > Imaging Tab > bottom of window > FocusMax > Select from choice of "FocusMax MultiStar" FocusMax Acquire Star" or "ACP Star Selection".

I'm not certain but I think if you have selected "FocusMax AcquireStar" in ACP for the autofocus method then the choice of filter during the autofocus run is configured in FocusMax > Preferences > Autofocus tab > Filter, and also see FocusMax > Preferences > AcquireStar tab > bottom of Window "Pointing filter".

Can't think of any other reason why the autofocus run is trying to use the blue filter...

William.

[Christian Hennes]

Hi again.
Stangely enough, I do not see the same paths that you're describing. I am using the "FocusMax AcquireStar" selection in ACP but for instance, I have no way of selecting the "pointing filter" in any of the FocusMax tabs...
Really puzzling!

[William Bristow]

Hi Christian.

Connect to the camera in FocusMax and then the drop-down menus for filter choice will be populated in FocusMax Preferences.

Give me an hour or so and I’ll attach some screenshots.

[William Bristow]

Hi again.
Stangely enough, I do not see the same paths that you're describing. I am using the "FocusMax AcquireStar" selection in ACP but for instance, I have no way of selecting the "pointing filter" in any of the FocusMax tabs...
Really puzzling!

These are screenshots from my system of FocusMax Preferences for use when FocusMax AcquireStar is selected as the autofocus method in ACP.

I don't use FocusMax AcquireStar routinely because FocusMax does not use a horizon mask and my observatory is located next to some tall buildings and trees and unfortunately when FocusMax is configured to use its internal AcquireStar method then the telescope is often trying to point to focus stars behind the obstructions.

For that reason I only use ACP Autofocus which does respect the horizon mask.

In the screen shots I've highlighted in red the important settings for when FocusMax is using AcquireStar for the autofocus method and to keep ACP's selection of filter for pointing and focusing you have to select "Current Filter" where shown.

For AcquireStar to know where the focus stars are and to find it's way around you have to choose an appropriate star catalogue on the PinPoint tab.

All the other important settings for using FocusMax AcquireStar as the autofocus method are in the red boxes, such as allowing the the telescope to slew to the zenith and minimum altitude (horizon) etc.

Most of this is outside of ACP's remit and when using FocusMax AcquireStar as the autofocus method then all these FocusMax settings have to be tested and proved to work reliably before configuring ACP to use AcquireStar because ACP just hands over full control of where the telescope is pointing, which filters are used for focus and pointing and which star catalogue is used for plate-solving while an Autofocus is performed.

If you want ACP to be in full control of where the telescope is pointing, which star catalogue is used to find the focus star and the filter used for plate-solving then use ACP Autofocus.

If nothing I've posted is relevant then Bob will be back tomorrow and will be better able to help....

HTH

William.

Prefs AcquireStar.jpg

Prefs Autofocus.jpg

Prefs PinPoint.jpg

Prefs Telescope.jpg