The Herschel ATLAS

The Herschel-ATLAS image compared with the full Moon and other images of the sky.
The ATLAS image compared with the size of the Full Moon as seen from Earth, and with the sizes of similar images from the Hubble Space Telescope (the Hubble Deep Field) and the SCUBA instrument on the James Clerk Maxwell Telescope in Hawaii. Click to enlarge.

The first data set from Herschel-ATLAS has been released to the astronomical community. This represents the largest public release of Herschel data so far and will be a powerful data-set for studies of galaxy evolution.  H-ATLAS have released images of a region of sky more than 60 times the area of the full moon (16 square degrees) containing more than 6000 galaxies, some of them seen at a time when the Universe was only 1/4 its present age.

The data released today were taken as part of the Science Demonstration Phase (SDP) of the Herschel mission in late 2009.  The H-ATLAS SDP data have so far provided exciting results in many areas of astronomy ranging from local galaxies to distant active galaxies to nearby debris disks forming planets around stars. The power of H-ATLAS is its wide-area coverage which means we can pick up extremely rare objects as well as see many more normal galaxies closer to home. The quality and scale of the data have been staggering and have led already to more than 20 papers on just this small patch of sky, which is only 1/30th of the final H-ATLAS area. The team are excited about what they will find next.

"The H-ATLAS SDP data-set surpassed all our wildest expectations, to have such a large impact with only 3% of the survey data is simply unprecedented" said Dr Steve Maddox who has been heavily involved in the data reduction and source extraction. Professor Rob Ivison added, "The speed at which we were able to analyse data from a brand new telescope and release it to the public is a testament to the hard work and thorough preparations of the Herschel Instrument and Control teams as well as the H-ATLAS data reduction team."

Dr Edo Ibar helped create the maps from the PACS instrument, said, "Even with the great data from the Herschel Observatory, it's still a difficult process to get from the raw data taken by the telescope to the beautiful maps we have today.  There were some glitches which meant that the standard way of doing things was removing some of our galaxies and we had to recover them. " He added, "Every galaxy counts!"

"Herschel's instruments have an incredible build quality" said Dr Simon Dye, . "They have survived a gruelling launch and a long journey to the telescope's observing point at 1.5 million kilometres away from Earth, and yet, the quality of data they are returning is as good as the quality measured in the lab. I feel privileged to be given the opportunity to work with this dataset."

To put things in some context, the deepest image of the sky previously undertaken at submillimetre wavelengths was of an area 600 times smaller than the H-ATLAS science demonstration field. This was the SCUBA Hubble Deep field image and took 51 hours. The H-ATLAS image took Herschel only 16 hours and is only 1/30th of the final survey region.

"We hope that now astronomers who are not directly involved in H-ATLAS will dive into this data-set and exploit the wealth of science which is bursting to be done with it" said Dr Loretta Dunne (one of the PIs of the survey).

The dataset can be accessed from www.h-atlas.org.

The SPIRE maps for the SDP release were made at Cardiff University and the PACS maps were made by a team of institutes across the world, led by the Astronomy Technology Centre, Edinburgh. The catalogues and optical associations were produced by the University of Nottingham.