The TERAPIX data centre has just released this spectacular image of the distant Universe, processed from images taken with the giant Megacam camera at the Canada-France-Hawaii Telescope.
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| The D1 deep CFHTLS field. |
| A gri-colored image produced at the Terapix data center |
| (click to enlarge) |
| (See below if you want a higher resolution (and much bigger !) image) |
This image has been obtained with "Megacam", a giant 36-CCD camera mounted at prime focus of the Canada-France-Hawaii Telescope (CFHT), which sits at the summit of the moutain of Mauna Kea, Hawaii.
This three-colour composite image was generated from 250 individual exposures taken with blue, green and red filters; each individual image measures 18,000 by 18,000 pixels.
This very deep image is used by astronomers to study the most distant objects in the cosmos and to investigate the dark matter and dark energy content of our Universe.
Production of this image involves several steps carried out at institutes around the world. After initial processing at CFHT and archiving at CADC (Canadian Astronomy Data Centre) each image is transferred to the TERAPIX data centre at the IAP (Institut d'Astrophysique de Paris).
| At TERAPIX the position of each individual exposure on the sky is accurately measured and this information is used to combine all images after a careful re-centering process.
TERAPIX also provides catalogues which record the total flux, the surface brightness, the position and the shape of each source detected in the final image. |
| In the stacked image presented above more than 600,000 objects are detected, most of which are very faint. Objects as faint as 26th magnitude are indeed easily visible.
The total field of view is around one square degree, or around four times the size of the full moon, as illustrated on the left picture (see below for technical details). |
Download: 
Image of the Canada-France-Hawaii Telescope Legacy Survey CFHTLS-D1 deep field (at half resolution of the original Megacam image - Warning! 10 MB jpg file)
See also: CFHT 25th anniversary Press Release CNRS Press Release INSU Press Release (Institut National des Sciences de l'Univers).
Technical description of the image:
This image is composed of three separate sets of images taken using the g* (blue), r* (green) and i* (red) Megacam broad-band filters. Total exposure times in each filter was 15.5, 4.8 and 2.1hr respectively.
The average full-width at half-maximum seeing on each stack, measured at the centre of the image, is around 0.9''. The final stacked images have a pixel scale of 0.186''/pixel and are 18000 x 18000 pixels in size (9x4 EEV CCDs of 2000x4500 pixels each, that is 700 MB of data per image). The limiting magnitude in the three bands is 26.5 AB magnitudes. The astrometric solution for the data, computed using the USNO-B astronomical catalogue of stars and galaxies, has an absolute accuracy of around 0.2 rms. Internal (i.e., band-to-band) root mean square (rms) uncertainties in the astrometric solution are much less than 1/3 of a pixel over the entire field of view.
More details: Megacam/Megaprime The CFHTLS survey
TERAPIX is funded by the French national research agency (CNRS/INSU), the Programme National de Cosmologie (PNC), the Service d'Astrophysique of the Commissariat à l'Energie Atomique (CEA), the Institut d'Astrophysique de Paris (IAP), and the European FP5 RTD contracts "Astrowise" and "AVO" (Astrophysical Virtual Observatory).
