Press Releases 1998

The NTT SUSI Deep Field

The NTT SUSI Deep Field project is described in ESO Press Release 01/98 (13 January 1998) and detailed information is available on the ESO Web at a dedicated webpage.

During this project, a total of 122 CCD frames were obtained in four colours [blue (B), green-yellow (V), red (r) and near-infrared (i-band)] with a total exposure time of no less than 31.5 hours. Total exposure times of 50400, 23400, 23400, 16200 seconds were obtained in the four bands, respectively. The frames cover a 2.3 x 2.3 arcmin `empty' sky field centered south of the high-redshift quasar QSO BR 1202-0725 (z = 4.7), located just south of the celestial equator.

These frames have been combined to produce a 'true' colour image in the sense that `blue', `green' and `red' represent the B-, V- and (r+i)-frames, respectively. This combined image is available in two versions, one with a high contrast that shows the faintest objects recorded ( ESO PR Photo 01a/98 ), and another that brings forward structural details in the brighter objects in the field ( ESO PR Photo 01b/98 ).

ESO Press Photo 01a/98 [JPG, 451k] NTT SUSI Deep Field (linear intensity scale) . Also available in a smaller version [JPG, 125k].

ESO Press Photo 01b/98 [JPG, 311k] NTT SUSI Deep Field (logarithmic intensity scale) . Also available in a smaller version [JPG, 81k].

This colour image shows objects as faint as 26th magnitude and it illustrates well the performance in deep imaging at good angular resolution with a relatively modest investment in exposure time at a 4m-class ground-based telescope. Of the approximately 500 galaxies detected in this field, the largest fraction are expected to be at redshifts smaller than z = 1 and about 20 percent to have higher redshifts, up to z = 4 and possibly beyond.

While the field size is relatively small, these observations are comparable to the deepest obtained at ground-based telescopes and they are unique in covering four bands with an image quality better than one arcsecond.

This is the caption to ESO PR Photo 01a/98 [JPG, 451k] and ESO PR Photo 01b/97 [JPG, 311k]. Smaller versions are also available: ESO PR Photo 01a/98 [JPG, 125k] and ESO PR Photo 01b/98 [JPG, 81k]. They accompany ESO Press Release 01/98 (13 January 1998) and may be reproduced, if credit is given to the European Southern Observatory.

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