The constellation is determined by the date of the solar calendar. 1999 The Gregorian calendar date on February 23rd of the lunar calendar is April 9th, and the constellation of that day is Aries.
Lunar calendar:1February 23, 999
Main branch: Jimao Chen Wuxinmao
Gregorian calendar:1Friday, April 9, 999 Aries
Source: Hua.com.