Named in memory of Guido Horn-d’Arturo (1879–1967), director of the Bologna Observatory for almost half a century and a talented astronomer far ahead of his time. A pioneer in the design and construction of multiple-mirror telescopes, he designed and utilized the world’s first such instrument, a 1.80-m zenith telescope at Bologna. In the 1920s he correctly interpreted the shadow-band phenomenon and attributed an important component of stellar scintillation to currents in the Earth’s stratosphere. Following a suggestion by Luigi Jacchia {see planet  (2079)}, he founded the magazine Coelum in 1931. (M 13178) _ _.