Telescope control. Fine slew pointing

[José Vicente Perea]

Hi Stellarium devel group

I usually manage the pointing of my telescope from Stellarium and everything works very well. The GOTO feature works fine. However I need to correct the final fine pointing from the hand control of the scope, but I don't know how to do it from the computer. As you probably know, the pointing accuracy could be good enough for large field eyepieces, but it is critical specially for small FOV cameras, and that's my case.

I am correcting this final fine pointing with the hand control of the telescope, and I would like to also use the computer for this final fine slew.

I have been googling but I didn't find any good solution.

Why Stellarium is not able to provide some kind of final control of the telescope ? It only can send GO-TO orders, but not the final fine pointing ? Or maybe I don't know how to do it.

In case Stellarium is not able to do this job. Do you know some extra software that allows that ?

My setup:

+ Celestron Nextar 130SLT

+ Laptop (Windows 10 x64) directly connected by cable to the hand control of the telescope

+ Stellarium 0.20.2

+ Camera BRESSER Deep-Sky FullHD and guider 1.25"

I am also wondering if the guiding feature of this camera (Autoguider ST-4 compatible) could be used from my telescope.

Thanks a lot for your help !

Cheers

Pere

[Georg Zotti]

Stellarium User Guide, section 15.2.1:

>Abilities and limitations
>This plug-in allows Stellarium to send ’slew’ (’go to’) commands to the device and to receive its
>current position. There are some scopes which additionally support ’sync’ commands to be received
>in order to update the internal pointing model of the mount. Some scopes also have the ability
>to abort a previous slew command. However, users should always be aware of the possibility for
>mount collisions and similar situations. You should always make sure that a slew does not cause
>parts of the telescope to collide with the environment or mount itself.
>Currently this plug-in does not allow satellite tracking unless the controlled telescope is an
>RTS2 system (see section 15.2.6), and is not very suitable for lunar or planetary observations. Many
>mounts can be set to a ’lunar’ tracking speed, you may prefer this.

Make sure you are using the right coordinate system (J2000.0 vs. equinox of date). Other than that, the accuracy depends on your mount. And yes, you may want to press the fine guidance keys on your mount.

[Hans]

Hi José,

José Vicente Perea wrote on 20201010:
...

> Why Stellarium is not able to provide some kind of final control of the
> telescope ?

Stellarium defers having a proper pointing model to the mount.

> It only can send GO-TO orders, but not the final fine pointing ? Or maybe I
> don't know how to do it.

What you're looking for may be to add a 'sync' point, but this depends on the
mount.
In stellarium_user_guide-0.20.3-1.pdf on http://stellarium.org/ section 15.2.1
we read "There are some scopes which additionally support ’sync’ commands to be

received in order to update the internal pointing model of the mount."

I however do not know if Stellarium can even send these sync command.

> In case Stellarium is not able to do this job. Do you know some extra
> software that allows that ?

That depends on your operating system and protocol choices. For instance I use
Linux and have KStars and Stellarium connected to my mount simultaneously via
INDI for things like GOTO's and next to that I manage the pointing model of my
mount with MountWizzard. But MountWizzard only supports 10micron mounts, not
your Celestron. Maybe you can use the Celestron tools next to Stellarium.

> I have been googling but I didn't find any good solution.

You're not the first to ask for this feature, but the developer group is small.
We welcome patches though ;-)

-- Hans

[Alexandros Kosiaris]

Hi,

Στις Σάβ, 10 Οκτ 2020, 19:05 ο χρήστης Hans <ha...@lambermont.dyndns.org> έγραψε:

Hi José,

José Vicente Perea wrote on 20201010:
...
> Why Stellarium is not able to provide some kind of final control of the
> telescope ?

Stellarium defers having a proper pointing model to the mount.

> It only can send GO-TO orders, but not the final fine pointing ? Or maybe I
> don't know how to do it.

What you're looking for may be to add a 'sync' point, but this depends on the
mount.
In stellarium_user_guide-0.20.3-1.pdf on http://stellarium.org/ section 15.2.1
we read "There are some scopes which additionally support ’sync’ commands to be
received in order to update the internal pointing model of the mount."
I however do not know if Stellarium can even send these sync command.

It can, at least via the INDI protocol, I 've contributed the code for it.  There is a "sync" button right under the "slew" one in the modal dialog.

> In case Stellarium is not able to do this job. Do you know some extra
> software that allows that ?

That depends on your operating system and protocol choices. For instance I use
Linux and have KStars and Stellarium connected to my mount simultaneously via
INDI for things like GOTO's and next to that I manage the pointing model of my
mount with MountWizzard. But MountWizzard only supports 10micron mounts, not
your Celestron. Maybe you can use the Celestron tools next to Stellarium.

> I have been googling but I didn't find any good solution.

You're not the first to ask for this feature, but the developer group is small.
We welcome patches though ;-)

-- Hans

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[Hans]

Hi Alexandros Kosiaris,

Alexandros Kosiaris wrote on 20201010:

> Hi, Στις Σάβ, 10 Οκτ 2020, 19:05 ο χρήστης Hans έγραψε:
> > Hi José,
> >
> > José Vicente Perea wrote on 20201010: ...
> > > Why Stellarium is not able to provide some kind of final control
> > > of the telescope ?
> >
> > Stellarium defers having a proper pointing model to the mount.
> >
> > > It only can send GO-TO orders, but not the final fine pointing ?
> > > Or maybe I don't know how to do it.
> >
> > What you're looking for may be to add a 'sync' point, but this
> > depends on the mount. In stellarium_user_guide-0.20.3-1.pdf on
> > http://stellarium.org/ section 15.2.1 we read "There are some
> > scopes which additionally support ’sync’ commands to be received
> > in order to update the internal pointing model of the mount." I
> > however do not know if Stellarium can even send these sync
> > command.
>
> It can, at least via the INDI protocol, I 've contributed the code
> for it. There is a "sync" button right under the "slew" one in the
> modal dialog.

Awesome ! And I learned something today :)

-- Hans