How Does Hubble Take Pictures of the Universe?

[Andy]

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 can't seem to get my head round it.

 

[Nereid]

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:
http://hubblesite.org/newscenter/newsdesk/archive/releases/2003/15/

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.
http://www.stsci.edu/hst/udf/index_html

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.

 

[russ_watters]

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.

 

[Andy]

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.

 

[Phobos]

Another satisfied customer here at PF!

 

[Andy]

I would have been satisfied if i was told to shut up and stop asking stupid questions!

lol.