Giovanni Battista Hodierna

Giovanni Battista Hodierna (1597-1660), also known as Odierna, was an Italian astronomer, priest and mathematician who served at the court of Giulio Tomasi, Duke of Palma, in Sicily. Using early telescopes, Hodierna compiled one of the first systematic catalogues of nebulae, star clusters and other faint deep-sky objects, published in 1654 under the title De Systemate Orbis Cometici, listing roughly 40 entries. His catalogue identified at least 19 real, verifiable nebulous objects, some of which were later independently rediscovered and catalogued by Charles Messier more than a century afterward, making Hodierna's work one of the earliest systematic surveys of what astronomers now call deep-sky objects. Hodierna also made observations of comets, wrote on optics and the workings of the telescope, and pursued studies in mathematics and natural philosophy alongside his ecclesiastical duties.