Named after Edward Charles Pickering - American astronomer (1846-1919), William Henry; American astronomer (1858-1938), Sir William Hayward; New Zealand-American engineer (1910-2004).
Pickering is 115 kilometres in diameter. Lava flow fronts are visible within the crater, and the source of the lava is Arsia Mons. The lava has flowed around the central peak of the crater. (wikipedia entry)
A crater is a circular depression likely created by an impact event. On Mars large craters are named after deceased scientists, writers and others who have contributed to the lore of Mars. Small creaters (less than 60km) are named after small towns and villages.