Bará Viñas, SalvadorTapia, Carlos E.Zamorano, Jaime2020-04-132020-04-132019Bará, S.; Tapia, C.E.; Zamorano, J. Absolute Radiometric Calibration of TESS-W and SQM Night Sky Brightness Sensors. Sensors 2019, 19, 1336http://hdl.handle.net/10347/21346We develop a general optical model and describe the absolute radiometric calibration of the readings provided by two widely-used night sky brightness sensors based on irradiance-to-frequency conversion. The calibration involves the precise determination of the overall spectral sensitivity of the devices and also the constant G relating the output frequency of the light-to-frequency converter chip to the actual band-weighted and field-of-view averaged spectral radiance incident on the detector (brightness). From these parameters, we show how to define a rigorous astronomical absolute photometric system in which the sensor measurements can be reported in units of magnitudes per square arcsecond with precise physical meaning.eng© 2019 by the authors. Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (http://creativecommons.org/licenses/by/4.0/)http://creativecommons.org/licenses/by/4.0/Night sky brightnessRadianceAstronomical magnitudesLight pollutionjournal article10.3390/s190613361424-8220open access