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What FORS2-DR1.0 contains

This release contains the first results of the ESO/GOODS program of spectroscopy of faint galaxies in the Chandra Deep Field South (CDF-S). 399 spectra of 302 unique targets have been obtained in service mode with the FORS2 spectrograph at the ESO/VLT in the period fall 2002 - spring 2003 (the first 9 masks, 348 slits), providing 234 redshift determinations. The median of the redshift distribution is at 1.04. The typical redshift uncertainty is estimated to be +-0.001. A further 17 masks have been observed during the period 2003 and early 2004, for which the reduction process has started and will be presented in a future release. Throuhgout the FORS2 survey 1" wide slits have been used, yielding a wavelength range of approximately 6000 to 10000 Å sampled at roughly 3.2 Å/pixel.

Each target is identified by it's position as derived from the ACS 5-epoch stack and a target identifier is constructed out of the target position, e.g., GDS J033206.44-274728.8. For each target we give the basic information such as magnitude (in the AB system) and colours as well as the measured redshift and associated comments (ASCII table). Furthermore we provide image cutouts in the ACS bands and a colour composite as well as a spectral preview through our WEB based archive. Through this archive one can also obtain information on the observing setup, such as slit length, orientation and a direct link to the raw data. A tar-ball containing all extracted 1-dim fits files of this release can be obtained from here.

Known caveats for this release

The wavelength calibrated 1-dim spectra were normalized to a relative flux scale. Since the response curve is based on standard star observations from a different observing program and throughout the FORS2 survey an observing setup omitting the order sorting filter was used, the flux calibration is not optimal. Particularly redwards of approx. 9000 Å, the spectral response function is problematic.

The spectral previews provided through the WEB based archive, show only a restricted wavelength range. For access to the full wavelength range we refer to the publically available fits spectra.

A small number of the color image previews do not cover the full 5"x5" FOV. This problem occurs when a target is located close to the edges of the image tiles which do not overlap.

Objects identified as stars by the stellar class parameter or the spectrum itself were asigned a fixed redshift of 0.000.

Phase 2 Material

In order to have a sufficient surface density of targets and fully exploit the red sensitivity of FORS2, spectroscopic targets have been selected according to the following criteria (all magnitudes are in the AB system in the ACS/GOODS filter set):

Primary catalog:          (i-z)>0.6,  z<24.5
Secondary catalog:   0.45<(i-z)<0.6,  z<24.5

The table below includes:

• FIMS files which can be loaded with the FIMS package for P70 (v 2.36, HP-UX-B.10.20, HP-UX-B.11.00, Linux-2.2.16, SunOS-5.7)
• Preimaging fields used as astrometric reference for the ACS imaging
• Observing Block names
• Target files: [RA, Dec, z, i-z] of spectroscopic targets. This list includes only sources from the input ACS catalog. The astrometry is given in the preimaging WCS (not the original ACS astrometry).

The table below includes all slit-masks observed and reduced to date. An image showing the FORS2 pre-imaging tiles (1-9) on top of the ACS GOODS-Field-South can be downloaded from here.

Send comments to <goods@eso.org>  Last modified: Tue Dec 14 17:37:30 MET 2004