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Question about hubble?

  1. Jan 18, 2004 #1
    I read recently on the BBC digital news service that Hubble has taken a picture of the Universe that dates back further than any other and to do this i stayed fixed on one spot of the Universe for 80 days. How is it that, it worked?

    Im sure i should know why, but just cant seem to get my head round it.
  2. jcsd
  3. Jan 18, 2004 #2


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    Not sure what your question is Andy.

    AFAIK, the deepest Hubble piccie was taken last year, of a small part of the outskirts of M31:

    This was deeper than the Hubble Deep South and North work, partly because it used the new ACS, rather than the older cameras (now retired).

    The Hubble Ultra-Deep Field (UDF) observations are now in progress; they involve accumulating multiple images of the one small region of sky over many, many orbits.

    Why don't they just take one piccie, in a single 80-hour 'exposure'? All kinds of reasons! Perhaps the most basic is the need to remove cosmic ray artifacts.
  4. Jan 18, 2004 #3


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    I'm sure he's talking about ultra deep field. A more recent release with some teaser photos: http://news.bbc.co.uk/1/hi/sci/tech/3387919.stm

    Long exposures are made because the longer you look at something, the more light you gather - its a cumulative effect. If you are looking at something 14 billion light years away, you need to look at it for a long time to get enough photons to form an image.
  5. Jan 19, 2004 #4
    Yea, i was trying to ask why it is that it needed to be pointed at one spot for such along time, but it i see it clearly now, or more clearer i should say. It took that long to get enough photons to form a detailed image rather than a rough one, which would hav on required a couple of days.

    I doubt that helped you either, but rest assured i now know what i set to find out.
  6. Jan 19, 2004 #5


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    Another satisfied customer here at PF!
  7. Jan 19, 2004 #6
    I would have been satisfied if i was told to shut up and stop asking stupid questions!

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