New Moon's Visibility Criterion Based on Photometric Data

Ahmed Kamil Ahmed

Abstract: The elongation (or arc of light) is the angular separation between the sun and the moon. It has taken as key factor that contributed to lunar crescent visibility criterion. Moreover, the time of crescent sighting, in case of topocentric calculations, was chosen as reference frame to assess the new moon visibility by taking its brightness contrast. The sky brightness conditions are measured during the clear nights of the lunar crescent that expected to be visible (i. e. clouds not present and a low aerosol loading). In addition, 43 of positive observations (successful) for lunar crescent from Malaysia, Teluk Kemang location, have been studied and analysed. The data employed to obtain the estimate values of sky brightness and have been correlated between moon elongation and solar altitude as well. The findings showed that the range of sky brightness for lunar crescent visibility is 0.05-167.802 lux. The moon elongation should be 11.331 and the solar depression angle should be 0.5 for the highest sky brightness value of 167.802 lux. Finally, the new moon visibility threshold, the moon elongation must be 8.5 0.1.

Keywords: Visibility, Sky Brightness, Moons Elongation, and Brightness Contrast