R. J. Mitchell, active in astronomy in the 1850s, was an assistant to William Parsons, 3rd Earl of Rosse. He studied at Queen's College, Galway[1] and was employed as a scientific assistant to Lord Rosse in 1853. He also taught the sons of Lord Rosse.
Mitchell was a talented observer and drawer who made many discoveries with Lord Rosse's 72-inch telescope, and it has been suggested that many of the discoveries claimed by Lord Rosse were actually made by Mitchell.[2] After leaving the employ of Lord Rosse in May 1858, Mitchell began a career in the Irish civil service.