The surface of the Moon as a calibration source for Na and K observations of the lunar exosphere

A procedure for calibrating observations of Na and K emission lines in the lunar exosphere with usage of the surface of the Moon as a calibration source is developed. The g-values of the resonance lines of Na, K, and other alkali metals are calculated for the total range of temperatures and radial heliocentric velocities of the Moon. The Na and K column densities above the north pole in the lunar exosphere were higher by about 30 and 50%, respectively, on October 24, 2019 in comparison with those on October 23, 2019. This increase of the Na and K content in the exosphere can be explained by an increased intensity of the bombardment of the Moon by the Orionid meteoroids. The Na content was also increased in upper Earth's atmosphere on October 24, 2019. Upper limits of the column densities of atoms of Li, Rb, and Cs in the lunar exosphere are also estimated.