The calibration technique for measurements of extended luminous ionospheric objects brightness (aurorae, meteors, artificial ionospheric clouds) during TV filtering observations is proposed. The calibration curve energy scale of the method is based on extrafocal images of one bright star with known spectral energy distribution. Level series of illuminance of input photocathode is obtained by stepwise change of the extrafocal image diameter of star. The number of illuminance levels within the TV tube dynamics range is of 10 - 15. The error of each measured brightness value is about 10%.
A. M. Evtushevsky,
Milinevsky P. Gennadi,
"Brightness calibration of extended luminous ionospheric objects", Proc. SPIE 2050, Airglow and Aurora, (23 November 1993); doi: 10.1117/12.164823; https://doi.org/10.1117/12.164823