Astronomical Surveys, Catalogues, Archives, Databases and Virtual Observatories

Astronomical surveys and catalogs are the main sources for the discovery of new objects, both Galactic and extragalactic. Archives and Databases maintain billions of astronomical objects; planets, comets, stars, exoplanets, nebulae, galaxies, and quasars. We will review the current background in astronomy
for further all-sky or large-area studies. Modern astronomy is characterized by multiwavelength (MW) studies (from gamma-ray to radio) and Big Data (data acquisition, storage, mining and analysis). Present astronomical databases and archives contain billions of objects observed at various wavelengths, and the
vast amount of data on them allows new studies and discoveries. Surveys are the main source also for accumulation of observational data for further analysis, interpretation, and achieving scientific results. We review the main characteristics of astronomical surveys (homogeneity, completeness, sensitivity, etc.), compare photographic and digital eras of astronomical studies (including the development of wide-field
observations), and describe the present state of MW surveys. Among others, Fermi-GLAST, INTEGRAL (gamma-ray), ROSAT, Chandra, XMM (X-ray), GALEX (UV), DSS1/2, SDSS, Hubble, Gaia (optical), 2MASS, IRAS, AKARI, WISE, Herschel (IR), NVSS and FIRST (radio) surveys and major astronomical archives and databases will be presented and discussed, as well as surveys and databases for variable and transit objects.