cheapest high resolution spectronomer in the market

[pixueto]

Dear all,

I've been thinking about getting into high resolution spectroscopy for a while but I don't know if I will be able to afford it. There are lots of questions that I would like to ask the gurus of this forum so hopefully, with your help, I will be able to get an idea about where I stand at the moment.

When I first took up astronomy I was very much interested in sectroscopy and had a go with the webcam and my star analyser-only got Vega's spectrum using a dobsonian and Rspec. Then I moved into imaging where I have been learning and obtaining some encouraging results. My current kit is a budget one; I have now a SW200P on a modded EQ5 so I can take guided images. I also use a Canon 350D. Now I've come to the point where I'm thinking of upgrading my mount to a HEQ5 or better which will set me back in excess of £800. I've been thinking about the possibility of going into high resolution specstroscopy instead of upgrading the mount.

So now the questions (loads of them, sorry!):

are there any high resolution spectrometers available for amateur astronomers? If so, which would be the cheapest one that will give me acceptable resolution? Will my EQ5 mount cope with that? Will that setup suffice?

Thanks for your help

[Merlin66]

IMHO moving up to serious slit spectroscopy is a challenge!

The commercial instruments like the Baader DADOS, Shelyak LISA or LhiresIII and the SBIG DSS7 or SGS start around $4000 and just keep going....They all work around f8 to f10...

Then you need to consider a "good" imaging camera to match the spectroscope. The ATiK314L is very popular...then a guide camera - Lodestar or equivalent...

The alternative is to build your own. This can certainly be done with basic DIY skills.

To guide a target star on a 25 micron slit takes a good mount...I use both a HEQ5pro and a NEQ6pro mount for spectroscopy...remember exposures are always a few minutes -and a normal "stack" up to 60min to get a good SNR.

Hope this helps.

[FraserClarke]

IMHO moving up to serious slit spectroscopy is a challenge!

The commercial instruments like the Baader DADOS, Shelyak LISA or LhiresIII and the SBIG DSS7 or SGS start around $4000 and just keep going....They all work around f8 to f10...

Then you need to consider a "good" imaging camera to match the spectroscope. The ATiK314L is very popular...then a guide camera - Lodestar or equivalent...

The alternative is to build your own. This can certainly be done with basic DIY skills.

To guide a target star on a 25 micron slit takes a good mount...

I'd agree with that Ken, but the 25 micron slit is still relatively big compared to typical pixel sizes on imagers. The ATiK314L for example has 6.5 micron pixels -- so as long as you get star images <~4 pixels on your images, you should be fine keeping a star on a slit.

One question is what you mean by high resolution? R=4000? R=10000? 50000? Or just anything with a slit?

[jsandse]

I dont have experience of modded eq5 but...

Well lets start with first easy question of whether you should upgrade your mount.

Can you take long exposure guided photographs - say 30 mins - with your current setup and still have perfectly round stars?

If that works and if there is enough capacity on your mount to put another 2kg on it for a spectroscope then you probably don't need to upgrade your mount for spectroscopy.

cheers

John

[pixueto]

I dont have experience of modded eq5 but...

Well lets start with first easy question of whether you should upgrade your mount.

Can you take long exposure guided photographs - say 30 mins - with your current setup and still have perfectly round stars?

If that works and if there is enough capacity on your mount to put another 2kg on it for a spectroscope then you probably don't need to upgrade your mount for spectroscopy.

cheers

John

Thanks for your help guys. The longest exposure I tried was 10 mins but you sort of answer my question. It's probably too much for my mount. The extra 2kg also being a problem. why do we need those long exposures?

[Merlin66]

Basically because the limited starlight is spread over a much larger area when you see the star's spectrum.

A star may be, say, 3 x 3 pixel in size on a "normal" astroimage.. when you disperse it into a spectrum it can cover 3 x 2000 pixel - the intensity is then (6000/9)= 666 times fainter - more than 8 magnitudes! The other issue is that spectroscopes are very inefficient - only about 20% - there's another loss of 80% of the available light. Spectroscopists are always looking for larger, and larger telescopes!!!

[pixueto]

I'd agree with that Ken, but the 25 micron slit is still relatively big compared to typical pixel sizes on imagers. The ATiK314L for example has 6.5 micron pixels -- so as long as you get star images <~4 pixels on your images, you should be fine keeping a star on a slit.

One question is what you mean by high resolution? R=4000? R=10000? 50000? Or just anything with a slit?

Yes, basically something with a slit. John mention something about a merlin spectrometer for $950?

[pixueto]

Oh dear! This is even more expensive than imaging?! What about concentrating on a few bright stars? Would that make things easier?

[FraserClarke]

Oh dear! This is even more expensive than imaging?!

Well, yes -- you need everything you need for imaging (except a filter wheel), and you need a spectrograph!

As you already have the star analyser, I'd suggest you keep using that and see how far you can push it with your current system. The more experience you get, the more you should be able to work out the issues and how to address them.

And if you want to push into full blown slit spectroscopy, the first step is definitely getting a system (telescope+mount+software) that works well for long images first. Knowing that bit works reliably will definitely make the jump to spectroscopy easier.

Also have look Yahoo spectroscopy group, which Merlin66 runs I believe;

http://tech.groups.yahoo.com/group/astronomical_spectroscopy/

[Merlin66]

Thanks for that Frazer!

Yes, the quantum leap to the "serious" slit spectroscopes is a heavy hit - especially when you're not 100% sure that's the direction you want to take for the rest of your life!

That's why I started producing the Spectra-L200 Kits as a low cost intermediate (R<5000) slit spectroscope. They are produced and sold on to members at cost.

[pixueto]

!!

[pixueto]

Thank you all for your help. I have now a better idea about where I stand at the moment. I think I' take your advice and concentrate on getting the most of my star analyser for a while and see how it goes. I'll try and enroll in Merlin66's yahoo group.

[pixueto]

Thank you all for your help. I have now a better idea about where I stand at the moment. I think I'll take your advice and concentrate on getting the most of my star analyser for a while and see how it goes. I'll try and enroll in Merlin66's yahoo group.