Constellations are determined by the date of the solar calendar. 1998 The Gregorian calendar date of May 2 1 day of the lunar calendar is1Monday of June 998, and the constellation of that day is Gemini.
Lunar calendar: May 21st, the year of Wuyin.
Gregorian calendar:1June, 998 15 Monday Gemini
Source of information: Central China Moon Network