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'newbie' to Spectroscopy


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Hi all,

As the title says, "'newbie' to Spectroscopy".

So I have just purchased a 'Paton Hawksley - Star Analyser 100' from SGL member billhiinge / Steve. I have been interested in doing this side of astronomy for some time. So a few questions... 

Q1. would it work with a digital compact camera, (either a Nikon CoolPix 900 or Olympus C2040), attached to my 'scopes, as per my signature. I do have a Phillips Toucam Pro 840K too! - The 'scopes will be mounted on either of the mounts as per my signature, (manual drive) - (both cameras have .TIFF rather than RAW for photos and .MOV for movies), or am I better off with the webcam?

Q2. 'prime' or 'afocal'?

Q3. what software do I need, (Windows or Linux), to interpret/translate the images? 

Q4. any other advice/recommendations on what/where to start?

Thank you for reading and looking forward to your replies.

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Hi Phil

Welcome to the wavy line section of the forum :smiley:

As noone else has chipped in allow an enthusiastic non expert to say a few words!. Can`t see a problem using your camera and the star analyser is an excellent start to spectroscopy. Never used mine with an eyepiece just had mine in front of the camera where the eyepiece should be. It can be a bit of a fiddle getting the star and its spectrum in the field of view as long as you get the grating to camera chip distance ok it should be fine. I had to have the star and spectrum diagonally in my field of view to get it all in and you then use the software to rotate it horizontally with the star on the left, spectrum to the right.

Do use John`s Windows BASS project software its free and available from John`s Yahoo group `Astrobodger`. It has an excellent user manual and is one of the best spectro packages available.

`Vspec` is another one and also `ISIS` but that has a fairly steep learning curve to it. `Rspec` is another excellent one but costs about £60 if memory serves.

I also bought quite a few books on the subject one of which is Ken`s excellent ` Astronomical spectroscopy for amateurs`.

Much more to say on the subject but enough for now :grin:

cheers

Steve

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Phil,

Welcome to the final frontier......

Answers:

1. You can start with any camera which can accept a 1.25" nosepiece to fit to the focuser on your scope. Fit the grating like a "normal" filter and see what results you get. Best to start on a brighter Type A star (Vega etc.)- these show some nice and easy absorption lines.

Read through the P-H Star Analyser info

http://www.patonhawksley.co.uk/staranalyser.html

2. Prime

3. See Steve's message - I also use BASS Project

4. I'd recommend downloading a copy of Richard Walker's excellent Spectral Atlas

http://www.ursusmajor.ch/downloads/spectroscopic-atlas-5_0-english.pdf

We can help as you climb the rocky road to success.

Onwards and upwards.

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Hi Philip,

If you use the Toucam you should be able to get some results straight out of the box. (I developed the Star Analyser  originally using exactly  this camera). Screw the SA100 onto the nosepiece, pop it in the telescope, point at Vega, focus carefully until the Hydrogen beta line is visible and away you go.  

The other cameras can be a bit more tricky as they have fixed lenses and there is not much experience of people using the Star Analyser in  that kind of configuration. As a minimum you will need to be able to manually control the exposure and focus. You could try with and without an eyepiece. With an eyepiece should work best in theory as you can focus the eyepiece at infinity first and  then place the grating between eyepiece and camera, keeping the light parallel through the grating. The problem is likely to be a rather short spectrum and limited resolution with the SA100 though. A higher dispersion grating eg the SA200 works better in this setup. You can see the equivalent (using an astro camera and DSLR lens here but the basic optical arrangement is the same.

http://www.threehillsobservatory.co.uk/astro/spectroscopy_19.htm

Alternatively for bright stars, you could try mounting the grating in front of the camera lens, without a telescope, similar to this. 

http://www.threehillsobservatory.co.uk/astro/spectroscopy_11.htm

Cheers

Robin 

www.threehillsobservatory.co.uk

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RSpec

http://www.rspec-astro.com/

is really nice software for beginners to use with video type cameras like the Toucam as it shows you the graph of the spectrum alongside the video image in real time but as Ken says it is not freeware, though it does have a limited time 30 day fully functional demo version which could help you get up and running.

Robin

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Thank you for the replies.  :icon_salut: 

No doubt more answers will follow in time along with my 'newbie' questions, of which I have another... 

Q. If I use my Phillips Toucam Pro 840K, should I remove my IR blocking filter from the nosepiece of my Mogg/webcam adaptor?  :icon_redface:

I presume the answer is going to be "Yes!" anyway.  :iamwithstupid:  

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Q. If I use my Phillips Toucam Pro 840K, should I remove my IR blocking filter from the nosepiece of my Mogg/webcam adaptor? 

Yep, this will make sure you get good sensitivity around the important H alpha region like the Ha emission line in Gamma Cas for example

http://www.threehillsobservatory.co.uk/astro/spectra_12.htm

and allow you to extend the range into the IR. Hot stars like Vega don't show much of interest in the IR, just O2 and H2O absorption bands from our own atmosphere but cool stars show strong broad molecular absorption bands stretching well into the IR. for example in Delta Vir here

http://www.threehillsobservatory.co.uk/astro/spectra_14.htm

(I've just realised this spectrum was first light for the prototype Star Analyser 100, over ten years ago now)

Cheers

Robin

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