A catalogue of quasars and active nuclei: 13th edition

Aims. This catalogue is aimed at presenting a compilation of all known AGN in a compact and convenient form, and we hope that it will be useful to all workers in this field. Methods. Like the twelfth edition, it includes position and redshift, as well as photometry (U, B, V) and 6 cm and 20 cm flux densities, when available. Results. The present version contains 133 336 quasars, 1 374 BL Lac objects, and 34 231 active galaxies (including 16 517 Seyfert 1s), almost doubling the number listed in the 12th edition. We also give a list of all known lensed and double quasars.