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Norton's Star Atlas is a set of 16celestial charts, first published in 1910 and currently in its 20th edition under the editorship ofIan Ridpath. TheStar Atlas covers the entire northern and southern sky, with accompanying reference information for amateur astronomers. The charts used in the first 17 editions of theAtlas were drawn by a British schoolmaster, Arthur Philip Norton (1876–1955), after whom theAtlas was named. Norton intended his star atlas to be used in conjunction with the highly popular observing handbooks written by the British astronomersWilliam Henry Smyth andThomas William Webb, and consequently most of the objects featured in those guidebooks were marked on the charts. TheAtlas also found favour among professional astronomers, earning it the reputation of the most widely used and best-known celestial atlas of its day.
Norton’s Star Atlas became highly popular because of its convenient arrangement of dividing the sky into six vertical slices, orgores, like portions of a globe. Each gore covered 4 hours ofright ascension, fromdeclination 60 degrees north to 60 degrees south, drawn on a projection specially designed by Norton. The north and south polar regions of the sky were covered by separate charts on a standardazimuthal equidistant projection, extending from the celestial poles to declination 50 degrees north and south.
For the first edition, Norton based his charts on theUranométrie Générale star catalogue compiled by the Belgian astronomerJean-Charles Houzeau. Constellation boundaries were represented by dashed lines meandering between the stars, for no official boundaries were then established. For the 5th edition of theAtlas, published in 1933, Norton completely redrew the charts, despite now suffering from severely impaired vision in his left eye due to a blood clot behind the retina. This time he used theHarvard Revised Photometry catalogue for the positions and brightnesses of the stars. In this 5th edition the Milky Way was included for the first time, and he incorporated the official constellation boundaries that had been laid down by theInternational Astronomical Union in 1930.
Norton redrew his charts yet again for the 9th edition published in 1943, extending the magnitude limit of the stars from 6.2 to 6.35. Positions were now given for the standardepoch of 1950, as against 1920 previously. The 9th edition charts remained in use up to and including the 17th edition ofNorton’s Star Atlas published in 1978, long after Norton’s death.
In addition to the charts,Norton’s Star Atlas also contained a reference section featuring practical information and data of particular interest to observers. Most of this text was the work of the publisher and various expert contributors. With each passing edition, the text grew into a reference handbook as essential for amateur astronomers as the charts themselves.
By the 1980s,Norton’s Star Atlas had come to look dated. In 1989 a totally new edition was published, the 18th, under the titleNorton’s 2000.0 to emphasize that its charts had been redrawn to the new standard epoch of 2000. These charts were computer-plotted by the cartographic company ofJohn Bartholomew and Son Ltd. in Edinburgh, Scotland, taking star positions and brightnesses from the most recent version of theBright Star Catalogue, the successor to theHarvard Revised Photometry. The total number of stars plotted was over 8800, reaching to magnitude 6.5. The text was extensively rewritten and reorganized under the editorship of the British astronomy writerIan Ridpath. For the first time in its history,Norton’s Star Atlas contained nothing by Norton himself.
A further break with the past came with the 20th edition in 2003 when publication of the title moved to New York, although the editor and contributors remained in the UK. For this edition the charts were replotted and the reference section heavily revised to reflect the latest advances in amateur astronomy.