Quote:
Originally Posted by gregbradley
I don't have a remote observatory but have 2 manual ones.
I have seen various scopes used for remote applications. Usually a high quality one.
It depends on the type of image and object you want to image.
Those categories are wide field, medium power for general objects and long focal length for galaxies and small objects or close ups of larger objects.
Tak FSQs and similar 105mm APO refractors are good for widefield imaging. Widefield is around 500-700mm focal length.
The downside of the FSQ is the need for constant refocusing with temperature drops. Other APOs will also need refocusing with temp drops but not as often as an FSQ.
Medium power would be around 1200mm focal length.
That would be for objects like Thors Helmet, Herschels Ray, Centaurus A, Sculptor galaxy and most nebulas. Generally speaking though Galaxies are more the realm of longer focal lengths.
Longer focal lengths like greater than say 1260mm is for galaxies, planetary nebulas, nebulas, globular clusters.
One consideration would be a scope that does not shift focus too much once its cooled down. Carbon fibre bodies are good for that. Carbon fibre truss telescopes and fan cooled mirrored scopes like RCs, CDKs etc.
The mount and focuser are more important considerations for a remote observatory. The mount has to be able to be accessed remotely. Not all mounts do that, in fact not many do and they are usually expensive.
If you go to the trouble and expense of building a remote observatory and I expect it would cost a fair bit (at a guess $20,000 to $25,000) then you would have to put a high end scope in it to make it worth it.
Also the seeing needs to be decent for long focal length scopes. They also need darker skies to get their best.
At home I have my observatory linked by serial cable to my home office and I run it from inside. I open up manually and close manually. I pick an object, frame and focus and begin a sequence of LRGB or Narrowband exposures. I check in on it from time to time to see if all is going well, focus is still sharp or refocus.
If something goes wrong its a short walk to the observatory to sort it out.
Despite using the same gear night after night its amazing how often something odd occurs that needs physical intervention. You'd have to factor that in with a remote observatory. It would not take much to need attention in person and I imagine there are many visits in the initial operation of one.
I use temp compensation on my focuser to automatically shift focus with temp shifts. This works reasonably well although refocusing is ideal.
If the problem you are solving is access to dark skies with good seeing that is far from your home then make it worth it with decent gear. Its hard enough with top gear.
Greg.
|
Greg,
Don’t underestimate the capabilities of the humble 8” f5 newt ( 1000mm FL ) which sits in my NexDome on the south coast
I’ve captured some fairly good Galaxy images down to mag 11 with my 8” under Bortle 3 skies. I even captured some good Galaxy images in Sydney under Bortle 8 skies with my 6” newt ( 900mm FL ) during the new moon period
But yes I agree bigger aperture longer focal length scopes are more suited for capturing Galaxies in larger scale and more detail
Here’s a some of my Galaxy images using the humble 8” and 6” newts
Cheers
Martin
