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Extinction problem

  1. Dec 16, 2008 #1
    I am currently writing up a photometric analysis of globular cluster M5 which I am doing from a set of images i have taken in the B,V and R bands. The CMD i have produced is obviously too red and faint due to the effects of extinction and reddening. As I am trying to calculate a distance using the luminosity of the tip of the RGB this effect is quite crucial. I know its E(B-V) that i need to calculate but i cant for the life of me think how to do it, any ideas? Thanks
  2. jcsd
  3. Dec 16, 2008 #2


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    It sounds like an instrument problem to me. Have you taken another set of images?
  4. Dec 17, 2008 #3
    The NASA Extragalactic Database (NED) gives extinction values in the direction of objects. For M5, scroll down the page here and you'll find the extinction values for a number of passbands. Please read the notes and accompanying papers to ensure the numbers are appropriate for what you're trying to do.
  5. Dec 17, 2008 #4
    Thanks, the NED looks like its got just what I need. Brilliant now I can get this typed up. Thanks once again uve made my week!!
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