Deep R-band counts of z ≈ 3 Lyman-break galaxy candidates with the LBT

Aims. We present a deep multiwavelength imaging survey (UGR) in 3 different fields, Q0933, Q1623, and COSMOS, for a total area of similar to 1500 arcmin(2). The data were obtained with the Large Binocular Camera on the Large Binocular Telescope. Methods. To select our Lyman-break galaxy (LBG) candidates, we adopted the well established and widely used color-selection criterion (U - G vs. G - R). One of the main advantages of our survey is that it has a wider dynamic color range for U-dropout selection than in previous studies. This allows us to fully exploit the depth of our R-band images, obtaining a robust sample with few interlopers. In addition, for 2 of our fields we have spectroscopic redshift information that is needed to better estimate the completeness of our sample and interloper fraction. Results. Our limiting magnitudes reach 27.0(AB) in the R band (5 sigma) and 28.6(AB) in the U band (1 sigma). This dataset was used to derive LBG candidates at z approximate to 3. We obtained a catalog with a total of 12 264 sources down to the 50% completeness magnitude limit in the R band for each field. We find a surface density of similar to 3 LBG candidates arcmin(-2) down to R = 25.5, where completeness is >= 95% for all 3 fields. This number is higher than the original studies, but consistent with more recent samples.