FORS1 MOS Spectroscopy

FORS1 MOS of Lyman-break galaxies

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The study of Lyman-break galaxies was the main spectroscopic programmeof the FORS1 Science Verification.

Science goals:

  • Push the FORS1 MOS to the limits and optimize its observational strategy and data reduction procedures for the specific case of faint galaxy MOS.
  • Provide pilot observations for future studies aiming at characterizing the abundance of high-redshift galaxies by luminosity, size, morphology, star formation rate and clustering.
  • Check and refine the photometric selection criteria for high-z galaxies.
  • Help tuning future wide-angle optical surveys to maximize the yield of  Lyman-break galaxies.
  • Provide galaxies in suitable redshift ranges for future spectroscopic observations with ISAAC.

Selection of the fields

For the SV proper the AXAF field was selected (Giacconi et al.,Proceedings of "Highlights of X-ray Astronomy", in honour ofJ.Truemper's 65th birthday Garching, Germany, 17-19 June 1998 Ed. B.Aschenbach ), given the availability of deep multi-colorimaging obtained with SUSI-2 and SOFI and derived catalogues producedby the EIS project. Data of the same type were also publicly available for a fieldincluding the WFPC-2 pointing in the Hubble Deep FieldSouth.Targets in this latter field were provided to the FORS1 commissioning teamand were observed by them in December 1998. Spectra of the objects in both the AXAF field and HDF-S have been reduced and analyzed in the same way and are both part of the present release.

Selection of the targets

Targets were extracted from the lists of U and B dropouts given inTable 5 and Table 6 of Rengelink, R. et al. 1998, A&A, submitted (astro-ph/9812190) for the AXAF field and in Table 9 ofda Costa, L. et al. 1998, A&A, submitted (astro-ph/9812105) for the HDF-S.
When no suitable candidate was available for the allowed range of positionsof a given slit, a random object in the field was chosen.