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GSO 16" Ritchey-Chretien telescopes

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Ronarbour's picture
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GSO 16" Ritchey-Chretien telescopes

Does anyone have a GSO 16" Ritchey-Chretien telescope possibly re-badged by various UK suppliers and be prepared to supply me with the following dimensions?

A) The tube balance point taken from the front of the tube.
B) The dimension across the flats of the tube octagons.

I want to be able to determine if the telescope can be housed in my planned observatory with a LISA spectrograph attached.

I would also be interested in owners views of these telescopes.

Replies can be private if preferred.

ronarbour@swonston.demon.co.uk

k.gurney's picture
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Hi Ron

Hi Ron

I have a humble 10in Altair Astro truss-tube RC (I think its  a re-badged GSO...). So can't help with dimensions but in general...

I am still 'commisioning' it properly but would say the first thing is to get a decent focuser. I now have a Starlight 3in Feathertouch with their  'posidrive' motorised add-on. I had hoopla with sourcing here, TS in Germany came good for me in the end. There are three moving parts in collimation which makes life 'interesting': focuser backplate, secondary, and primary. A Laser, Cheshire, and CCD inspector (respectively) all came in handy here.

It sits on a MESU 200 mount (friction drive). My AZEQ6 was not up to it.... I would guess a mount like the MESU or better would be required

Kevin

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GSO 16" Ritchey-Chretien telescopes

Hi Kevin,

Many thanks for your useful comments.
I had wondered about the design of the focuser and the Starlight 3in Feathertouch with the posidrive motorised add-on does indeed look very interesting.
I gather from what you say that a two mirror system and a focuser that can be collimated independently can be somewhat tedious to tame.
My hope is to mount  the 16" model on a Paramount MEll.

Kind regards,

Ron

k.gurney's picture
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Hi Ron

Hi Ron

On collimation: The problem for me was that there are probably as many web pages detailing RC collimation as there are installatons.... I think I now have a collimation procedure worked out. If you get hold of the 16in RC, let me know and I can supply my notes.

The MEII looks to be a mighty beast! (I have to be able to take mine down occasionally...)

cheers

Kevin

k.gurney's picture
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Hi Ron

Hi Ron

On collimation: The problem for me was that there are probably as many web pages detailing RC collimation as there are installatons.... I think I now have a collimation procedure worked out. If you get hold of the 16in RC, let me know and I can supply my notes.

The MEII looks to be a mighty beast! (I have to be able to take mine down occasionally...)

cheers

Kevin

Ronarbour's picture
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GSO 16" Ritchey-Chretien telescopes

Hi Kevin,

Thanks for the offer. I shall certainly remember that, I want to keep as much of the little hair I have left!

Kind regards,

Ron

Andy Wilson's picture
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GSO 10" RC

Hi Ron,

I also own a 10" Altair Astro (GSO) RC. I understand that Altair made some kind of modification to the GSO RCs before selling them. I think it was something to do with the mirror cell but I don't know exactly what. They have stopped selling them now.

I've done collimation once and it was a bit of an ordeal. I expect it is one of those things that once you have done it a few times then it gets much easier. I've found it to be very stable and appears to hold collimation well. Though as I am also using it for spectroscopy, I don't worry too much about having the collimation absolutely spot on as this won't affect the spectrograph resolution, just the throughput and so SNR.

I also upgraded to the Feathertouch Focuser and found it to be rock solid. I've not bothered with a motorised focus as I am in the observatory and I can tweak the focus if needed. Though I find the whole telescope and focuser to be extremely stable and so I rarely need to adjust it, except due to seasonal temperature changes.

If you get a 16" then I'll be very interested to hear how you get on with it. I wonder about one day upgrading to a larger GSO RC. Though for me the choice was also about a compromise between matching the focal ratio with my LHIRES III spectrograph, and keeping the focal length short so that I have a reasonable field of view in the guide camera.

Best wishes,

Andy

Ronarbour's picture
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GSO 16" Ritchey-Chretien telescopes

Hi Andy,

I'm glad to hear that the RC system and focuser retains good correct focus over a reasonable time as mine will be operated from a separate control room from which I also control a C14. The GSO RC will also take part in Supernova searching so maintaining good focus over long periods lasting several hours and hundreds of images, will be a big benefit.

I plan to reduce the focal ratio to better match the optical system of the LISA.

Anyway, thanks Andy for your experiences with GSC RC and I will certainly relay my thoughts if I do proceed in getting one.

Regards,

Ron

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10" Altair RC

I've used a 10" Altair RC quite a bit and found that once I got the tension in the focuser sorted out, focus seems to say pretty tight for several hours. We had a couple of instances where it changed abruptly during the night, but that was some time ago now and seemed to occur only with a heavy CCD.

Ronarbour's picture
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GSO 16" Ritchey-Chretien telescopes

Hi Grant,

Was this the original focuser and when you say heavy, how heavy? I'm keen to know an approximate weight.

Regards,

Ron

Grant Privett's picture
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CCD

Its the original focuser.

A Starlight H18 and a Starlight filter wheel.

It didnt happen after we put some tension of the focuser. Besides which, we were fast slewing an awful lot, so the scope would go from near zenith to near horizon in just a couple of minutes.

We just installed a C11 RASA instead. Can't use filters but it has a much wider field of view.