Coelostat for solar observing

[Merlin66 (Ken)]

Has anyone made a Coelostat? I have the BAA write-up for guidance but any practical feedback welcome.
I can't find a source of 1/10 wave front surface mirrors - ideally around 12" diameter...

[bojan]

Back in '80-s I motorised an existing coelostat mechanism (fork mounted mirror, 10" or so in diameter) . I believe it was in use for some time on Zagreb's Astronomical observatory.
The main purpose of using the coelostat is in permanent setup - it requires a lot of space for all the components of the system and it is not very practical if you don't have it and if it is for occasional use only.

[Merlin66 (Ken)]

Yes, it would be a fixed arrangement.
Looking at feeding an array of white light/ Ha - single and double stack/ CaK scopes, based on a 150mm f8 OTA.
The usage would be limited by the weather!!!

[bojan]

Once I was playing with this idea (coelostat instead of GEM... you can get away without large dome as well), and asked Chi Quin Optical for a flat mirror, they could do it, but it was expensive - more than paraboloid (which was not a surprise)... so I gave up.

However, now you've got me re-thinking.. Maybe my future observatory in Seymour (for general astro-phography and spectroscopy as well) could be much better bang for a buck if I consider coelostat..
Hmmm ..
I will be back on this shortly..

EDIT:
Bartel's software that I was planning to use supports coelostat arrangement (and associated field rotation).