The sky brightness when the rising sun is in eclipse

Part of the "Xia-Shang-Zhou Chronology Project" is the study of a historical record of "double dawn" and its astronomical interpretation. We used the light meter on ordinary cameras to determine the sky variation during normal sunrises and sunsets, set up a way of calculating the variation when the rising sun is in eclipse, and identified the range and intensity of the double dawn phenomenon. For this, we organized a mass participation of the observation of the 1997-03-09 eclipse in Xinjiang Province. The observations are in good agreement with our model calculation and prove that an eclipsed sunrise could indeed give rise to the phenomenon of "double dawn".