The VLT observations of the HDF-S NICMOS field: photometric catalog and high redshift galaxy candidates

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We present the deep UBVRI observations of the HDF-S NICMOS field obtained as part of the Science Verification of the VLT Unit 1 telescope. The images have been used to construct object catalogs and to obtain photometric redshifts. The effective field of view is ≃ 70×70 arcsec², and the formal 5σ limiting magnitudes (in a 2 FWHM aperture) are 26.3, 27.8, 27.5, 26.9, 25.2 in the U, B, V, R and I bands, respectively. Thanks to the sub-arcsecond image quality, relatively long exposure time, and large collecting area of the VLT, this is the deepest set of multicolor images ever obtained from a ground-based telescope. Galaxy counts have been derived independently in each band, and show no significant departures from previous data from wider areas. A multicolor photometric catalog of all the galaxies selected in the R band has also been obtained and used to derive photometric redshifts for all galaxies with R ≤ 26.5, using also the J,H and K magnitudes from the NICMOS deep observations. A significant fraction (≃ 28%)of the galaxies is placed at z≥ 2. Among them, six robust candidates are found at z ≥ 2.5.