The Preparation of the Revised 3C Catalogue of Radio Sources

New observational data are used to make a complete revision of the 3C catalogue, which should now provide a complete and reliable list for all sources with flux greater than $$9 \times 10^{-26}\enspace \text {w.m}^{-2} \enspace(\text {c/s})^{-1}$$ at 178 Mc/s and for which δ > −05°. The correction of the observations for the effects of confusion is described in detail, and the analysis of these errors is verified by comparison of the original 3C measurements with new measurements now available. The new catalogue is compared with the original, and it is shown that the number counts of sources remain almost unchanged, in agreement with new observations by Scott and Ryle.