Ekos

[Jasem Mutlaq]

Thank you for sharing the details Hy! I actually thought that folks used it
for accurate slewing, much like TPoint and thought Why? Platesolving is
already much easier than to model the whole sky. I didn't know that its
primary purpose today is accurate tracking without guiding.

We have a similar solution in INDI with INDI Alignment Subsystem, but this
is purely used for GOTOs and not adjusting RA/DE tracking on the sky. I
don't even recall if the AP command sets include such a command to adjust
tracking rate, and most mounts do not support this. It can be done with
SkyWatcher and Celestron mounts nevertheless.

However, it seems to be a niche requirement given that guiding is working
well for most people. Definitely adding support to this at the INDI layer
would be beneficial but it requires a lot of time and effort.

--
Best Regards,
Jasem Mutlaq



On Wed, Feb 19, 2025 at 6:44 PM Hy Murveit <murveit at gmail.com> wrote:

> Let me be a little more specific. SPCC does sky modeling, that is, it
> (along with a companion program) captures images of the sky every degree or
> two in a square grid, plate solves all those images, and computes a
> function comparing where the mount thinks it is vs where it actually is.
> This allows it to vary the tracking rates in RA and DEC, so that things
> like refraction, and tube bending, and polar alignment error etc can be
> compensated for, and folks can image for many minutes without guiding (at
> least on scopes with optical absolute encoders that remove all periodic
> error). This process takes, I believe, about an hour or so (though you can
> shortcut it by just modeling the DEC arc you plan to image tonight). People
> with permanent installations do it and forget about it. People who move
> their scopes to dark sites every time they use them need to do this
> modeling every night--though you can start before it is astronomically dark.
>
> So, my A-P 1100 mount without absolute encoders and without SPCC is
> similar to yours (John) in that it has basically the same capabilities,
> except perhaps better materials/workmanship so it tracks a little better
> and handles more weighty loads. Add in SPCC and it can do the same or
> better without guiding.
>
> So, Wolfgang, sky modeling is needed for those folks who like to image
> without guiding. The A-P clientele are definitely in that category--at
> least the ones that buy SPCC. Sky modeling for big telescopes was used for
> more accurate slewing, but now for amateur imaging telescopes is used for
> guiding-free imaging.
>
> However, guiding works--at least to some level--well enough for many
> people to think the modeling is not needed. I suppose it's nice not to have
> to guide etc.
>
> Hy
>

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