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App/program that allows you to adjust spectrums of light?

  1. May 3, 2014 #1

    I'm looking for a web-site or something with images from galaxy's and nebulae that allows you to adjust which spectra of light the image portrays.
    I know that the images shown of galaxys usually are "translated" into our visible spectrum of light, but I'd like to be able to adjust which spectra I see myself. Is that possible?

    is it true that when telescopes make these images, that they actually record all the spectra? or is the data not even available? (i.e. do they choose which spectra to record before the image is taken?)

    This would be really awesome, if such a website/program exists!
  2. jcsd
  3. May 4, 2014 #2


    Staff: Mentor

  4. May 4, 2014 #3
    Thanks! I see now that the telescopes don't actually take color images, but greyscale images at different filters. I didn't know that!
  5. May 4, 2014 #4


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    There's a wealth of spectral data on stars, galaxies and quasars available at the SDSS web site at http://mirror.sdss3.org/ [Broken] I attached an image of the type of spectrum you can get. It will take a little bit of learning to learn how to find the spectra (they are under "Optical Spectra"), but it is well worth it. At SDSS, they run a preliminary imaging run, then select which objects they want spectra on, and then take the spectra. SDSS is able to get spectra on about 500-1000 objects at a time for each exposure.

    Attached Files:

    Last edited by a moderator: May 6, 2017
  6. May 5, 2014 #5
    Thats cool! but this data contains only the total light of the entire object, right? So you can't see an image made of different wavelengths
    Last edited by a moderator: May 6, 2017
  7. May 5, 2014 #6


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    It is common practice to use filters to block undesired frequencies. With modern computers photons can be deselected based on frequency, which is often more efficient.
  8. May 5, 2014 #7


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    A spectrum is a plot where the light is broken up into different wavelengths. The plot I uploaded shows the light intensity on the Y-axis vs wavelength on the X-axis.
  9. May 7, 2014 #8
    To be overly explicit, a spectrum is exactly an image of the different wavelenghts from some source. It does however not make a picture in the sense that you have any spatial information.
  10. May 7, 2014 #9


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    Right. If you want images at different wavelengths, the SDSS site has 5 different images taken through 5 different filters, called ugriz. You can download the fits files for these images.
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