Constellations are divided according to birthdays in the solar calendar (new calendar, Gregorian calendar) of the year of birth. On September 30th in the Gregorian calendar, the constellation is Libra.
The following is the date division table of constellations. Compare the birthday of the solar calendar with the one below and you will know what constellation it is.
Aries (03/2 1-04/20)
Taurus (04/2 1-05/20)
Gemini
Cancer (22 June 2006-22 July 2007)
Leo (07/23-08/22)
Virgo (08/23-09/22)
Libra (09/23- 10/23)
Scorpio (10/24-11/22)
Sagittarius (11/23-12/21)
Capricorn (12/22-0119)
Water bottle: 0 1/ 20- 02/ 18
Pisces (02/ 19-03/20)