Constellations are determined by the date of the solar calendar. On April 27th, 2004, the solar calendar date is June 14, and the constellation of that day is Gemini.
Lunar calendar: April 27th, o four years.
Main Branch: Jiazi, Wu Geng, Shen Jia
Gregorian calendar: June, 2004/KLOC-Monday, 0/4 Gemini
Source: Hua Wang.