An area of sky with minimal absorption by neutral hydrogen gas. The Lockman hole is approximately 15 square degrees in size, centred on RA 10h 45m, dec. +58°, in Ursa Major. Because of the lack of absorption it is the ideal location for sensitive studies of extragalactic objects. Hence this region has been studied in detail over a wide range of wavelengths, from radio to gamma rays. It is named after the American astronomer Felix James Lockman (1947– ), who drew attention to it in 1986.