I am currently at 4,200m, at the summit of Mauna Kea in Hawaii, using UKIRT - the United Kingdom's Infra-Red Telescope. We are using UKIRT to carry out the UKIDSS - the UKIRT Infra-red Deep Sky Survey.
Actually, UKIDSS is not one survey, but five similar surveys which will take 7 years to complete! The five surveys are:
- Large Area Survey (orange in the all-sky map below)
- Galactic Plane Survey (purple)
- Galactic Clusters Survey (green circles)
- Deep Extragalactic Survey (blue squares)
- Ultra Deep Survey (red dot within the blue square)
Both the Large Area Survey and the Ultra Deep Survey are looking for very distant galaxies (cities of stars). By "Ultra Deep", astronomers mean "ultra-sensitive", and so the Ultra Deep Survey will be able to detect very faint and very distant galaxies.
Running five surveys in parallel makes it a very efficient survey - if one of the surveys cannot be done on a particular night, another one can be done instead. For example, it may be slightly hazy as it is as I type this, which would mean that we cannot see the very faint galaxies that the Ultra-Deep Survey is looking for, but we can look at the star-filled galactic plane instead, which is easy to see through haze.
For the galactic plane survey, exposures are only 14 minutes long; for the ultra deep field, exposures are 75 minutes long!
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