Dome slaving in between imaging or imaging events

In the past week I installed LesveDome in our domed observatory and since yesterday it is up and running. I have noticed, however, that due to its weight of 450kg the dome affects stability of the GM3000 mount. I would thus like to slave the dome in between imaging or in between imaging events (e.g. with a script). Furthermore the slit of our dome is quite large, some 30 degrees wide, so I have set the tolerance in SGP to 10 degrees to limit the amount of dome movements, but ideally I would like to be able to rotate the dome 10 degrees too far to the west, so that I can make use of the full width of the slit. I think the latter can be achieved by giving the home position a deliberate 10 degrees westerly offset, but perhaps there are better options?

Still I could do with some advice regarding the slaving in between imaging or imaging events.

thanks in advance,
NicolĂ s

We don’t currently have anything like this. We’ll consider it for future releases.

Thanks,
Jared

Hi Jared,

thanks for your reply. Would it in the meanwhile be possible to do this with a VBS? Is it possible to switch on and off the slaving using that? If so, a script at the end of an event could switch on slaving, wait for some preset time, and switch off slaving again. The only problem is, that I have no idea how to create such a script, so some help would be greatly appreciated.

In the meanwhile I have given the dome a 20 degrees offset to the real world, which allows for a 30 degrees window before the dome has to move. So far it seems to work well.

Thanks,
NicolĂ s

Probably not…and certainly not easily.

I’ll have to think on this some. I may have a solution to this which is “not too bad” on our end. Essentially we would force the move between frames but not preclude the “normal” slaving moves that are happening due to the “Allowed Error” being exceeded. The idea is that this doesn’t break our normal slaving logic (so your dome still follows your mount when it is not in a sequence). But this means that the chances that your dome needs to move during an image are a lot lower. Currently you’re almost guaranteed that your dome will move during an image. This would at least make that chance a lot lower.

Essentially your slaving error grows during each frame and eventually grows large enough that we move the dome. But forcing it between frames means that the slaving error drops between each frame and should hopefully not be exceeded during the next frame. I think this could also be annoying with lots of small frames (dome moving between each one) so maybe we use something like 25% of the “Allowed Error” as the precision for slaving between images.

Anyways, probably needs more thought but I think we can make this work.

Thanks,
Jared

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Hi Jared,

I realise that this needs some proper thoughts indeed. Currently I mainly do 2 minute exposures, although the mount has proven that 20 minutes could easily be achieved. Living close to the Dutch airport Schiphol I have (at least for the moment) chosen to keep exposures short to avoid that I will be mainly collecting planes, not stars…

best wishes,
NicolĂ s

I would also like to see this feature added :slight_smile:

Jared:
I’ll have to think on this some. I may have a solution to this which is “not too bad” on our end. […] but I think we can make this work.

Hi Jared,

I would like to bring this issue to your attention again, as I am really in need of an option to avoid dome movements during (long) exposures. Would be best if it could be toggled on/off (so “on” meaning only dome-movement in between exposures, “off” meaning dome movement allowed at al times. The latter would be more convenient for lighter domes with narrower shutters, while the former would be better for heavvy domes with wide shutters like ours.

Thanks,
NicolĂ s

This is something we may add an option for in an upcoming release. But currently there is no time span on completing it.

Thank you,
Jared

HI Jared,

thanks for your answer, I will have to be patient then.

cheers,
NicolĂ s