How to calculate Tianbao Day in the Yellow Calendar?

From the Preface written by Tang Dynasty poet Teng: "Things are valuable, and the dragon lantern shoots outstanding people in the bull market, and Xu Ru walks to Fan Chen's bed." It turns out that Wang Bo used two allusions here. The first one said that things have essence, and there are treasures in the sky. The light of Longquan sword points directly to the night between the 28 stars in the sky and the cowshed. It means that Hongzhou has treasure. The latter statement means that Xu Confucian, a native of Nanchang in the Eastern Han Dynasty, was poor and unwilling to be an official, but he was good friends with Chen Fan. Fan Chen specially ordered one.