![]() The brightness of the zodiacal light, for the observations carried out at high altitudes above sea level, is larger than that deduced at low altitudes by mean factors are 1.5 and 2 for small and large elongations respectively. The maximum brightness of zodiacal light occurs during the new moon, which is 1.29 times the brightness at lunar age 10 days. The ratios of the zodiacal light brightness at minimum solar activity to that at maximum solar activity are 1.3 and 1.7 for the observations carried out at low and high altitudes above sea level respectively. Photoelectric observational model of the zodiacal light brightness and polarizations in the blue, yellow and red colors has been suggested during quiet solar activity. Nawar studied the spectral photometry of the zodiacal light near the tropic of cancer at Daraw and Abu-Simble in Egypt by a photometer in the BVR regions. The conclusion of their results was that the first light appeared from the east at a = −17.35˚ and the first appearance of color difference (true dawn) was at a = −14.25˚, while the beginning of the true dusk was at a drop of the sun under the horizon by at a = −14.9˚. Miethe and Lehmann reported observations of the dawn and dusk in Aswan of Egypt (24˚6'N, 30˚45'E and 160 m Elev.) in the winter of 1908 and by a camera made especially for this purpose. Humans can distinguish about 7 to 10 million different colors just name them and build an instrument that identifies them. The transition to night is usually complete when the sun is depressed 17˚ - 19˚ below the horizon. When the sun reaches a depression of 10˚ - 15˚ below the horizon, the intrinsic glow of the upper atmospheric layers begins to appear together with starlight, and the illumination conditions gradually approach those of night. ![]() The study of the twilight of various types is extremely important for large segments of the society, especially astronomers, to study the planets during the twilight for the length of the twilight in the summer months in the upper latitudes. ![]() The light magnitude of the full night after the pseudo dusk was found to be 20.77 ± 0.93 mag./arcsec 2, while it was found to be 22.17 ± 0.1 mag./arcsec 2 before the pseudo dawn. The altitude of the sun for the true dusk was found to be -14.38 ° ± 0.91 ° and for the beginning of the pseudo dusk was found to be -14.86 ° ± 0.91 ° and the end of the pseudo dusk is -17.8 ° ± 0.7 °, while for the beginning of the true dawn it was found to be -14.19 ° ± 0.52 ° (for high confidence -14.71 °) and for the pseudo dawn was found to be -18.62 ° ± 0.82 °. The measurements were taken when the device was directed to the position of sunrise and sunset at the horizontal angle of the sunrise or sunset and at five degrees above the horizon during the entire monitoring period. In 20, the Sky Quality Meter (SQM) was used in four regions in Malaysia to measure the brightness at night, pseudo dawn, true dawn, true dusk and pseudo dusk. This study is concerned with determining the altitude of the sun under the horizon to the beginning and the end of the true and pseudo dawn and dusk.
0 Comments
Leave a Reply. |
AuthorWrite something about yourself. No need to be fancy, just an overview. ArchivesCategories |