During the ASTAR 2000 (Arctic Study of Aerosol and Radiation) campaign, conducted in March and April 2000 in the vicinity of Svalbard height dependent aerosol optical depth (AOD) in the spectral range from 350 nm to 1050 nm with an airborne Sun photometer were measured. The measurements were done on board of the aircraft behind a quartz window with well-known transmission. Observations were performed on board of the Alfred-Wegener-Institute research aircraft Polar 4 during 18 flights between the 15 Mach 2000 up to 19 April 2000 with the operation base Longyearbyen (78° 13′ N, 15° 38′ E). Based on the height dependent aerosol optical depth for four selected wavelengths (412 nm, 532 nm, 861 nm, 1023 nm) and the Ångström parameter Alpha (spectral slope) and Beta (AOD at 1000 nm) between 55 m and 7288 m the extinction coefficient (AOD per kilometer) can be calculated for selected wavelengths, for example for LIDAR or satellite comparison and validation. For special comparison is also the height angle pf the Sun is included.