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Author Topic: Spectroscopy software!  (Read 2418 times)

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Offline gasman

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Spectroscopy software!
« on: 15:22:26, 26 August, 2007 »
Hi folks
I have been dabbling in Spectroscopy for a while with the little `Star Analyser` 100 lines/mm grating and using `Vspec`the free spectroscopy software package to process and plot spectra taken through my DMK camera.
To get a true image of the spectra taken you need to allow for the ccd response of the camera used ie some are more blue sensitive than red ( or is it the other way around?) anyway an image taken and processed allowing for the cameras response then gives a true spectrum of the star. Vspec is claimed to be able to do this ccd response correction but I am not having much luck with it as a reference profile taken for my camera should be ok for any class of star taken- but it isn`t and gives very misleading corrections. I have stumbled across IRAF which is a Unix package and is running on my laptop under Cygwin. Iraf is supposed to be better at ccd reponse correction but it seems to have a quite steep learning curve and I`m finding it difficult to find a tutorial or such like which could show me the way and I wondered if any among the group have indeed used IRAF maybe for spectroscopy and how they found how to use it please.
Cheers
Steve

Offline davemahoney

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Re: Spectroscopy software!
« Reply #1 on: 17:08:30, 26 August, 2007 »
Hi Steve.
I have been trying to start Spectroscopy for a while, (it's a cloud thing :()
This site may be of use to you.

Dave.
http://www.astro.uiuc.edu/~kaler/sow/spectra.html
Skywatcher ED80 pro
Celestron 114mm short newt.
ASTSC1C Webcam.
Fuji finepix s3500.
Bresser 10x50 bins.
Switched Systems electronic focuser.
And a couple of eyepieces and filters.

Offline gasman

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Re: Spectroscopy software!
« Reply #2 on: 19:08:56, 26 August, 2007 »
Hi Dave
Ta for the link. I seem to be ok at understanding the physics of it all, the various emission/absorption lines and how they could be formed. When taking shots of spectra your camera gives its own imprint to the image by how sensitive it is in the blue or the red and software like Vspec has library profiles of stars which you can divide by the image you take to come up with a reference profile which can then be used for any other star to take an image of. You take an image, run it through Vspec and divide your image by the reference one you have saved which then gives you a ccd adjusted spectrum. The problem I have is that my reference spectrum is only good for the type of star used to produce it  for example if I use an A class star to make my reference profile it seems fine for other A class stars but not all types of star which its supposed to. I`ll keep at it.
Cheers
Steve

Offline davemahoney

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Re: Spectroscopy software!
« Reply #3 on: 19:20:35, 26 August, 2007 »
As a newcomer to this subject, i understand that reference spectra is available on the web.
I'll take a look and if i find something i'll let you know.

Dave.
Skywatcher ED80 pro
Celestron 114mm short newt.
ASTSC1C Webcam.
Fuji finepix s3500.
Bresser 10x50 bins.
Switched Systems electronic focuser.
And a couple of eyepieces and filters.

Offline robin_astro

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Re: Spectroscopy software!
« Reply #4 on: 23:30:12, 01 September, 2007 »
Hi Steve,

Your instrument response should be reasonably universal. For example here are the response curves for my Star Analyser/modified webcam setup using two different stars of class A and K.
http://mysite.wanadoo-members.co.uk/astro2/spectroscopy_5.htm
Yours should look similar. If not we need to look again at  the steps in vspec you are using to see where things are going wrong.

Robin
www.threehillsobservatory.co.uk/astro/astro.htm
Vixen VC200L GPDX, Skysensor 2000 
Modified web and video cams
ATK16-IC, Spectrographs

Offline Ambermile

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Re: Spectroscopy software!
« Reply #5 on: 00:17:18, 02 September, 2007 »
Steve - I was going to post a message here suggesting you wait for Robin to dive in  - but it looks like he beat me to it! 

I leave you then, in the capable hands of Mr Star Analyser himself  :D


arthur

Offline jaleebi22

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Re: Spectroscopy software!
« Reply #6 on: 07:15:05, 31 December, 2014 »
After all a greater part of astronomy is about science. No offence to the beautiful images. ..........!!!!!!!!!!!!!
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