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Extended or point source?

  1. Aug 20, 2009 #1
    If you were using a single radio telescope (not an interferometer) how could you tell whether a radio source was a point source or extended source?

    I have searched the internet far and wide for many hours trying to answer this - I know what the difference between a point source and extended source is, but I'm not sure whether the question is asking for a simple or technical explanation. Is it something to do with the radio telescope data or how the radiation from the source is spread out on the dish when its received?
    Last edited: Aug 20, 2009
  2. jcsd
  3. Aug 20, 2009 #2


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    Gold Member

    I assume you mean the usual in-effect single-pixel radio telescope at a single point in time. Then it is pretty much impossible to tell the difference, I think. The usual method then is to look at different points at different times. i.e. scan out the image over time. You can then detect its size, assuming its pretty much a constant source and really bigger than one pixel.
    Jim Graber
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