A catalogue of star positions which have been determined absolutely and with the highest possible precision from a compilation of many observations. Absolute positions are determined by recording the times of transit across the meridian. Combination of the results from several observatories helps to reduce the effects of both systematic and random errors. A series of fundamental catalogues has been produced and published in Heidelberg, Germany. The current version, known as FK5, contains improved data on the 1,535 stars of magnitude 7 and brighter also listed in FK3 and FK4. Work is in progress on an Extension to FK5 that will cover about a thousand stars in the magnitude range 5-7 selected from the FK4 Supplement, plus around two thousand others in the magnitude range 6.5-9.5.