Estonian astronomer and astrophysicist (1893-1985) who spent his postwar career at the Armagh Observatory in Northern Ireland and won several important prizes, including the J. Lawrence Smith Medal, the Gold Medal of the Royal Astronomical Society, and the Bruce Medal. ALS signed “Ernst Julius Opik,” one page both sides, 5 x 8, blindstamped Armagh Observatory letterhead, August 18, 1950. Letter to Cambridge astronomer Arthur Beer, in part: "I think you have all the numbered and unnumbered Armagh publications. These are: Astronomical Obs—ions…Armagh Catalogue, 1859…Second Armagh Catalogue, 1886…An Historical Account of Armagh Observatory, 1883…Contributions from the Armagh Observatory…Armagh Observatory Leaflets…I know that these have all been sent to the Cambridge Observatories. If, however, some are lost, we will be glad to provide the missing if available." In fine condition.