The constellation is determined by the Gregorian calendar date. 1July 27th, 996, the Gregorian calendar date is September 9th, and the constellation of that day is Virgo.
Lunar calendar:1July 27, 996
Branches and Branches: Bingzi Ding Jiyou Oil
Gregorian calendar:1Monday, September 9, 996 Virgo
Source: Hua.com.