"The last quarter of 's life was spent on projects that grew out of his earlier work at Greenwich Observatory as assistant observer to Astronomer Royal Bradley. From studies of Bradley's records Mason prepared tables for and he was able to improve Mayer's Tables of the Moon by comparing them with the Greenwich records. was established by in 1767, immediately after his appointment as Astronomer Royal, and it has appeared annually ever since. In the first issue the latitude and longitude of are given as found by Mason and Dixon in 1761. The comment follows that "it is probable that the Situation of few Places is better determined." To the Almanac for 1773 Mason contributed a catalogue of stars. The preface, written by Maskelyne, states: To this are annexed... a Catalogue of 387 fixed Stars.... adapted to the beginning of the year 1760... calculated from the late Dr. Bradley's Observations by Mr. Charles Mason, formerly his Assistant. ...After the Catalogue follow some Memoranda... communicated by the same Mr. Mason."