The English astronomer John Flamsteed (1646-1719), the first astronomer royal, was the author of an important set of star catalogs.

John Flamsteed was born at Denby near Derby on Aug. 19, 1646, the only son of Stephen Flamsteed. John attended the Free School in Derby until he was forced to leave because of illness. After a brief period of rest and treatment, he entered Jesus College, Cambridge, in 1670 to study astronomy.

Flamsteed's interest in astronomy was stirred by the solar eclipse of 1662, and besides reading all he could find on the subject he attempted to make his own measuring instruments. He came to astronomy more or less self-taught, and yet he became known through an article in 1670 in the foremost scientific journal of the day, Philosophical Transactions of the Royal Society. At Cambridge he observed the planets and the moon, and by these observations and research into written sources he deduced great quantities of data. After earning his degree in 1674 and taking Holy Orders, Flamsteed was invited to London by Sir Jonas Moore, Governor of the Tower, who offered him a private observatory in Chelsea. But events took a different course: it had been pointed out to King Charles II by his advisers, of whom Flamsteed was one, that if more accurate astronomical data were available to seamen, fewer ships and men would be lost. Sir Christopher Wren built an observatory at Greenwich, and Flamsteed was appointed in 1675 "our astronomical observator," the first astronomer royal.

Flamsteed's position was difficult: he had no instruments and no assistants. A clergyman without a living, he took private pupils in mathematics and astronomy to supplement his salary so that he could purchase the instruments he needed. For 13 years he worked single-handedly, with a sextant of 7-foot radius and other instruments that he had provided for himself, and made at least 20,000 observations. He improved the existing tables of known star positions and the tables of the moon's motion, and he attempted to amend existing lunar and planetary theories. Although Flamsteed repeatedly asked for a transit instrument, he was never provided with one; his observations could be made solely with his sextant, which gave only relative positions of the stars.

Isaac Newton badly needed the data from Flamsteed's observations to complete his lunar theory, but Flamsteed regarded them as his own property. The two quarreled, and eventually Flamsteed was obliged to turn his data over to the Royal Society, of which Newton was president. Shortly thereafter, in 1712, the data appeared without Flamsteed's consent, under the title Historia coelestis Britannica. Flamsteed died on Dec. 31, 1719, before the printing of his own edition was complete (1725).

Flamsteed was probably the first to make good use of a timepiece in addition to the usual angle-measuring instruments. He found the annual variation in the position of the polestar to be 40". His greatest achievement was perhaps his British Catalogue of 2884 Stars, which included critiques of many earlier catalogues.

Further Reading

• Francis Baily, Account of the Reverend John Flamsteed (1935), is the main source of information. This originally made up the third volume of Flamsteed's Historia coelestis Britannica (1725), completed posthumously. Flamsteed is covered in Eugene Fairfield McPike, Hevelius, Flamsteed and Halley (1957), and Antonie Pannekoek, A History of Astronomy (1961).