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Old 21-09-2018, 09:18 PM
47Tucanae (Helen)
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Thinking about scope for spectroscopy

I'm quite interested in spectroscopy and wondering about telescope choices that might facilitate this in the future. (I know- google is my friend, but in case you felt like having a chat about what you've been doing...)

I had had my heart set on a Dobsonian - I love deep sky objects (who doesn't?) and a great big light bucket sounded wonderful - and they look so simple, too. However I just read that you can't do photography with the usual Dobsonian mount. So maybe a Schmidt-Cassegrain would be a better choice; perhaps spending extra on the mount and upgrading the scope later?

However I'm also really interested in radio astronomy so wondering if I should just focus my energies and expenditure there. But you know, when hubby says 'you ought to have a telescope', you ought to put put a couple of suggestions out there. In case Santa is feeling generous.

Last edited by 47Tucanae; 21-09-2018 at 10:36 PM. Reason: spelling
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Old 21-09-2018, 10:21 PM
GOTO (Geoff)
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Hi Helen, I’ve been using a rather small 150mm reflector for ages but recently changed to a SCT telescope . It has given much better results and my students have been able to get within one spectral subclass with ease. I use the real-time spectroscopy software and the Star analyser 100. Tom Field from RSpec has been awesome help.
Cheers Geoff
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Old 21-09-2018, 10:50 PM
47Tucanae (Helen)
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Hi Helen, Iíve been using a rather small 150mm reflector for ages but recently changed to a SCT telescope . It has given much better results and my students have been able to get within one spectral subclass with ease. I use the real-time spectroscopy software and the Star analyser 100. Tom Field from RSpec has been awesome help.
Cheers Geoff
Thanks Geoff. That sounds promising. Would you mind sharing your current scope's specs?

I've just been looking at the RSpec website - it does look awesome. I'm sure there are other packages. I'm quite computer literate and don't mind tinkering with software. I'm not all that worried about astrophotography - happy to enjoy the images made by others - but being able to learn about spectra and the chemistry of stars with my own data is really appealing.
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Old 22-09-2018, 09:28 AM
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Merlin66 (Ken)
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Helen,
Spectroscopy can be challenging and a bit intimidating to the novice. The good news is there are plenty of resources available to assist.

My forum and Webpage (See signature) provides all the basic info and useful Webpage links you need to get started.

Using a grating (SA100 or SA200) provides a great introduction to spectroscopy. I call it "Spectroscopy 101".
To obtain "useful" spectral images you need at least a camera and lens (fit the grating in front of the lens - "Objective grating") and some means of tracking to give longer exposures (>30 sec)

The next step is to fit the grating in front of a camera body in a telescope ("Grating in Converging beam") this allows you to record the spectrum of fainter objects in some detail. A small telescope and EQ mount is needed.
You could start with an ED80 on the HEQ5 mount. This would also provide some good views of the moon, planets and deep sky objects.

Then comes "Spectroscopy 201" - where a slit spectroscope is use to give even more spectral resolution. This is the type of instrument used by all "serious" amateurs. Unfortunately these are not cheap and currently Shelyak and Baader are the only two commercial suppliers -Shelyak: ALPY, LISA, LhiresIII, and Baader DADOS. Paul G. has recently designed a 3D printed instrument which is being tested by a few amateurs.

All this is detailed on the Webpage.

To allow analysis of the spectral image you'll need a processing software.
RSpec is OK to start with, but you should also consider some of the more capable software (as used by the ProAm users)
Buil's ISIS, Valerie's VSpec and John's BASS Project are very good. I recommend and use BASS Project which meets all my need for spectroscopy and with the spectroheliograph.

Hope this helps. Any questions/ concerns just let us know - we're here to help.
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Old 25-09-2018, 08:53 AM
47Tucanae (Helen)
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Originally Posted by Merlin66 View Post
Helen,
Spectroscopy can be challenging and a bit intimidating to the novice. The good news is there are plenty of resources available to assist.
...

All this is detailed on the Webpage.

...

Hope this helps. Any questions/ concerns just let us know - we're here to help.
Thanks, Ken, that's a really useful reply. I've got a lot of learning to do before I think about high-end stuff... and maybe there's potential there for some community resources.

I've installed RSpec and had a bit of a look at that... as usual this software is never intuitive but the materials are quite informative.
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Old 28-09-2018, 11:17 AM
Granada
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There's also a good article about RSpec in the October issue of Australian Sky & Telescope mag that got me thinking about spectroscopy too
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Old 28-09-2018, 11:39 AM
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Merlin66 (Ken)
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Yeah, a good introductory article on basic spectroscopy.
Doesn't go into the "science" but hopefully enough "Ohh Ahh" to encourage amateurs to give spectroscopy a go.
A grating can be used "in the converging beam" in almost any telescope (>f5 preferred to minimise aberrations.)

Paton Hawksley, who supply the Star Analyser gratings has an on-line calculator to assist in evaluating the distance the grating should be placed in front of the camera for optimum results.
http://www.patonhawksley.co.uk/calculator/
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Old 29-09-2018, 11:51 AM
47Tucanae (Helen)
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Originally Posted by Merlin66 View Post
Doesn't go into the "science" but hopefully enough "Ohh Ahh" to encourage amateurs to give spectroscopy a go.
It was in fact that article that made me go 'ooh I could have a crack at this...' after looking at the antennae on John Bolton's roof and thinking 'why not...'
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