Sky Quality Meter cross-calibration for the NixNox project

Abstract

Twelve SQM-L night sky photometers have been calibrated to determine their internal precision and differences in response. Amateur astronomers around Spain, under the supervision of the Spanish Astronomical Society (SEA, Sociedad Española de Astronomía), will use these photometers to locate and characterize sites with dark skies well suited to perform astronomical observations (NixNox Project). A simple experimental setup has been built to obtain zero offsets for each photometer in order to correct all the observations.