Andrew Claude de la Cherois Crommelin

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Andrew Claude de la Cherois Crommelin (February 6, 1865 – September 20, 1939; A.C.D. Crommelin) was a British astronomer. He was born in Cushendun, County Antrim, Northern Ireland, but his parents moved to England when he was a small child. He worked at the Royal Greenwich Observatory and went on several solar eclipse expeditions.

An expert on comets, his calculation of orbits of what were then called Comet Forbes 1928 III, Comet Coggia-Winnecke 1873 VII, and Comet Pons 1818 II, in 1929, showed that these comets were one and the same periodic comet. The comet thus received the rather unwieldy name "Comet Pons-Coggia-Winnecke-Forbes". In 1948, he was posthumously honored when the comet was renamed after him alone (today, in modern nomenclature, it is designated 27P/Crommelin). This is similar to the case of Comet Encke, where the periodic comet is named after the person determining the orbit rather than the possibly-multiple discoverers and re-discoverers at each apparition.