CALIFA, the Calar Alto Legacy Integral Field Area survey: II. First public data release

We present the first public data release (DR1) of the Calar Alto Legacy Integral Field Area (CALIFA) survey. It consists of science-grade optical datacubes for the first 100 of eventually 600 nearby galaxies, obtained with the integral-field spectrograph PMAS/PPak mounted on the 3.5 m telescope at the Calar Alto observatory. The galaxies in DR1 already cover a wide range of properties in color-magnitude space, morphological type, stellar mass, and gas ionization conditions. Two different spectral setups are available for each galaxy, (i) a low-resolution V500 setup covering the nominal wavelength range 3745-7500 [Angstrom] with a spectral resolution of 6.0 [Angstrom] (FWHM), and (ii) a medium-resolution V1200 setup covering the nominal wavelength range 3650-4840 [Angstrom] with a spectral resolution of 2.3 [Angstrom] (FWHM). We present the characteristics and data structure of the CALIFA datasets that should be taken into account for scientific exploitation of the data, in particular the effects of vignetting, bad pixels and spatially correlated noise.