What is the constellation on September 5th?

Since constellations come from western countries, they are calculated according to the date of birth in the Gregorian calendar.

If the 9.5 you give is Gregorian calendar, it is Virgo.

If you give the lunar calendar, you should convert it to 9.5 of the lunar calendar in the year when you were born, and see what month it is in the Gregorian calendar.