The constellation is determined by the Gregorian calendar date. 1July 23, 977 The Gregorian calendar date is September 6, and the constellation of that day is Virgo.
Lunar calendar: July 23rd in year of the snake.
Branch: Ding Siwu and Shen Bingyin
Gregorian calendar:1Tuesday, September 6, 977 Virgo.
Source: Hua Wang.