A robust and extended characterization of the point spread function (PSF) is crucial to extract the photometric information produced by deep imaging surveys. Here we present the extended PSFs of the Sloan Digital Sky Survey (SDSS), extending over 8 arcmin in radius for all filters (u, g, r, i, z). We illustrate with an example how the PSF models

The Romanesque architecture in the Iberian Peninsula was introduced through the Way of Saint James, as one of the main routes of pilgrimage of the XI century. This building fever would let us verify the ecclesiastical canons on the orientations of the Christian churches, as one of their main characteristics is definitely their eastwards orientation

Two major features of structure in galaxy discs: the long-term presence of spiral arms, and the continuous presence of OB stars concentrated in the arms, can be explained if a spiral density wave in the stellar population interacts with star-forming gas in the disc. With a recent method we are able to perform accurate characterization of the

The effective or half-light radius has become a very popular choice for characterising galaxy size, but it measures the concentration of light within galaxies and thus does not capture our intuitive definition of size which is related to the edge or boundary of objects. We define a new physically motivated measurement of size for galaxies, R 1

Accurate distances to individual Milky Way stars provided by Gaia have allowed us to derive stellar age distributions from colour─magnitude diagrams (CMD) representative of the thick disc and the local halo. The CMD for the kinematically selected halo stars showed an enigmatic double main sequence. The blue sequence had been linked to a major

We use a sample of 33 H II regions with high and intermediate resolution spectroscopy to analyze the radial distribution of different elements in the Milky Way. This sample covers Galactocentric distances from 6 to 17 kpc, which have been revised using Gaia DR2 parallaxes. We calculate physical conditions and chemical abundances using updated