Danjon Number and RGB-colors in Total Lunar Eclipse: 2000-2017

Número de Danjon y color RGB en los Eclipses Totales de Luna: 2000-2017

By: N. Falcon, A. Ortega

Main Information

Volume:
Vol.51-N3 / 2018 - Ordinario
Section:
Color
Pages:
50025:1-14
DOI:
http://doi.org/10.7149/OPA.51.3.50025
Type:
Research papers / Trabajos de investigación
Language:
Spanish
Attachments:
Keywords:
Danjon number, Total Lunar eclipse, digital colors, atmospheric optical thickness.

Número de Danjon, Eclipse Total de Luna, Color digital, espesor óptico atmosférico.
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Abstract

The apparent magnitude and chromaticity of the lunar disk during the maximum phase of a total eclipse of the Moon inform about the atmospheric optical thickness and the average column density of aerosols in the Earth's atmosphere. The estimation of the magnitude of the total lunar eclipse has been used for paleoclimatology studies and has been correlated with global volcanic activity; hence the importance of its quantification. However, the qualitative scale used to determine the magnitude and chromaticity, known as Danjon's number, is not sufficient to unambiguously characterize these magnitudes. A methodology is sought to determine a well-defined scalar, which links the Danjon number to the RGB digital color of the photographs, called the Danjon Factor (FD); and the results obtained for all the total eclipses of Luna occurred in the period 2000-2017. It is concluded that the Danjon Factor is an effective measure of the magnitude and chromaticity calculable through the digital RGB color in the Total Lunar Eclipses.


La magnitud aparente y la cromaticidad del disco lunar durante la fase máxima de un eclipse total de Luna informan sobre el espesor óptico atmosférico y la densidad media columnar de aerosoles en la atmósfera terrestre. La estimación de la magnitud del eclipse lunar total se ha empleado para estudios de paleoclimatología y se ha correlacionado con la actividad volcánica global; de allí la importancia de su cuantificación. Sin embargo la escala cualitativa usada para determinar la magnitud y cromaticidad, conocida como número de Danjon, no es suficiente para caracterizar unívocamente estas magnitudes. Se propone una metodología para determinar un escalar bien definido, que vincula el número de Danjon al color digital RGB de las fotografías, denominado Factor de Danjon (FD); y se presentan los resultados obtenidos para todos los eclipses totales de Luna acaecidos en el periodo 2000-2017. Se concluye que el Factor de Danjon es una medida eficaz de la magnitud y cromaticidad calculable a través del color digital RGB en los Eclipses Totales de Luna.

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