Geological Chronicle
Located in the central lunar highlands south of Hipparchus and east of both Ptolemaeus and Alphonsus, Albategnius is one of the largest craters of Nectarian age. Its level interior forms a walled plain surrounded by a high, terraced rim with a somewhat hexagonal outline. Impacts, valleys, and landslips have heavily eroded the outer wall, which attains a height above 4,000 metres along its northeast face. A crater chain runs along the northwest wall, and the smaller crater Klein breaks the rim in the southwest.
Offset to the west of the crater midpoint is the central peak, Alpha Albategnius, extending just under 20 kilometres north to south and about half that in width. The peak rises to an altitude of roughly 1.5 km, with a tiny, relatively fresh crater at its top. Because Alpha Albategnius is only a fraction of the size observed in central peaks of comparable younger craters, the rise appears to have been modified since it originally formed. In the surrounding area, nearly parallel scars form channels running roughly in a north–south line, bent slightly to the southeast.
Albategnius is believed to appear along the lunar terminator in an early sketch drawing by Galileo in his 1610 book Sidereus Nuncius. Earlier cartographers assigned different names to the feature: Michael van Langren called it Ferdinandi III Imp. Rom. on his 1645 map, and Johannes Hevelius called it Didymus Mons. Giovanni Riccioli later named the crater after astronomer and mathematician al-Battānī, and the International Astronomical Union formally adopted the Latinized designation Albategnius in 1935.