Great Observatories Origins Deep Survey

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Science & Reason on Facebook: GOODS - The Great Observatories Origins Deep Survey: Great Observatories uncover black holes & hidden objects. ESOcast 21 / Hubblecast 39 (multicast): The Great Observatories Origins Deep Survey (GOODS) T...

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GOODS - The Great Observatories Origins Deep Survey: Great Observatories uncover black holes & hidden objects.

ESOcast 21 / Hubblecast 39 (multicast): The Great Observatories Origins Deep Survey (GOODS)

Today's telescopes study the sky across the electromagnetic spectrum. Each part of the spectrum tells us different things about the Universe, giving us more pieces of the cosmic jigsaw puzzle. The most powerful telescopes on the ground and in space have joined forces over the last decade in a unique observing campaign, known as GOODS, which reaches across the spectrum and deep back into cosmic time.

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This is a very special "multicast". We'll be exploring a unique collaboration between some of the world's most powerful telescopes both on the ground and in space. Now, to do this, we've set up a similar collaboration between the ESOcast, the Hubblecast, the Spitzer Space Telescope's "Hidden Universe" (Dr Robert Hurt) and the Chandra X-Ray Observatory's "Beautiful Universe" (Megan Watzke).

It's the combination of deep observations from many different telescopes that makes this project so important. The longer a telescope spends looking at a target, the more sensitive the observations become, and the deeper we can look into space. But to get the full picture of what's happening in the Universe, astronomers also need observations at a range of different wavelengths, requiring different telescopes. These are the key ideas behind the Great Observatories Origins Deep Survey, or GOODS for short.

The GOODS project unites the world's most advanced observatories, these include ESO's Very Large Telescope, the NASA/ESA Hubble Space Telescope, the Spitzer Space Telescope, the Chandra X-ray Observatory and many more, each making extremely deep observations of the distant Universe, across the electromagnetic spectrum. By combining their powers and observing the same piece of the sky, the GOODS observatories are giving us a unique view of the formation and evolution of galaxies across cosmic time, and mapping the history of the expansion of the Universe.

Now, this is not the first time that telescopes have been used to give us extremely deep views of the cosmos. For example, the Hubble Deep Field is a very deep image of a small piece of sky in the northern constellation of Ursa Major. This revealed thousands of distant galaxies despite the fact that the whole field is actually only a tiny speck of the sky, about the size of a grain of sand held at arm's length.

Now, with GOODS, many different observatories have brought their powers to bear on two larger targets, one centred on the original Hubble Deep Field in the northern sky, and one centred on a different deep target, the Chandra Deep Field South, in the southern sky. The main GOODS fields are each 30 times larger than the Hubble Deep Field, and additional observations cover an area the size of the full Moon.

The NASA/ESA Hubble Space Telescope observed the GOODS regions at optical and nearinfrared wavelengths, to detect distant starforming galaxies among other things. Now, Hubble spent a total of 5 days observing the fields, spread over five repeat visits. Each of these was separated from the previous one by about 45 days. Now, by spreading out the observations like this, Hubble was able to watch for new supernovae appearing over the months, providing key information for studying the expansion and acceleration of the Universe due to the mysterious dark energy.

In the next couple of years, ALMA, the Atacama Large Millimeter/submillimeter Array, currently under construction on the same plateau as APEX, will begin its first science observations. Also observing at submillimetre wavelengths, it will have much greater sensitivity than APEX, and resolution even better than Hubble. ALMA will revolutionise our understanding of the early Universe by revealing many more distant, dustobscured galaxies that cannot be seen at all by visible light and infrared telescopes.

These projects are an excellent example of how great observatories are joining together, across the electromagnetic spectrum, to give us a more complete view of galaxies over the history of the Universe. Already, astronomers have written over 400 papers based on these data, with even more in the pipeline! And on top of that, the observations of the GOODS fields will continue in the future.

These patches of the sky will be prime targets for the next generation of telescopes both on the ground and in space, and astronomers around the world use these data to learn new things about the Universe from them for many years to come ...


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