Ground based in situ observations of aerosol_absorption_coefficient at El Tololo (CL0001R) using filter_absorption_photometer. These measurements are gathered as a part of the following projects GAW-WDCA and they are stored in the EBAS database (http://ebas.nilu.no/). Parameters measured are: aerosol_absorption_coefficient in aerosol (volume_absorption_coefficient_in_air_due_to_dried_aerosol_particles)