Auroral all-sky camera calibration

Abstract

A two-step procedure to calibrate the spectral sensitivity to visible light of auroral all-sky cameras is outlined. Center pixel response is obtained by the use of a Lambertian surface and a standard 45W tungsten lamp. Screen brightness is regulated by the distance between the lamp and the screen. All-sky flat-field correction is carried out with a 1m diameter integrating sphere. A transparent Lexan dome at the exit port of the sphere is used to simulate observing conditions at the Kjell Henriksen Observatory (KHO). A certified portable low brightness source from Keo Scientific Ltd was used to test the procedure. Transfer lamp certificates in units of Rayleigh per Ångstrøm (R/Å) are found to be within a relative error of 2 %. An all-sky camera flat-field correction method is presented with only 6 required coefficients per channel 2012) to quantify the radiance in photometric units (Hunten et al., 1956). This paper presents a two-step procedure to calibrate to sensitivity the all-sky cameras at the Kjell Henriksen Observatory (KHO).