Subsequent HST Observations
An HDF counterpart in the southern celestial hemisphere was created in 1998: the HDF-South. Created using a similar observing strategy, the HDF-S was very similar in appearance to the original HDF. This supports the cosmological principle that at its largest scale the universe is homogeneous. The HDF-S survey used the Space Telescope Imaging Spectrograph (STIS) and the Near Infrared Camera and Multi-Object Spectrometer (NICMOS) instruments installed on the HST in 1997; the Hubble Deep Field has since been re-observed several times using WFPC2, as well as by the NICMOS and STIS instruments. Several supernova events were detected by comparing the first and second epoch observations of the HDF-N.
A wider survey, but less sensitive, was carried out as part of the Great Observatories Origins Deep Survey; a section of this was then observed for longer to create the Hubble Ultra-Deep Field, which was the most sensitive optical deep field image for years until the Hubble Extreme Deep Field was completed in 2012. Images from the Extreme Deep Field, or XDF, were released on 26 September 2012 to a number of media agencies. Images released in the XDF show galaxies which are now believed to have formed in the first 500 million years following the Big Bang.
Read more about this topic: Hubble Deep Field
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