In September 2026 the son-eomneun days fall on 1, 10, 19, 20, 29, 30. 6 in all. These are days whose lunar date ends in 9 or 0 — long the first thing people check before moving house or opening a shop.
September 24: 추석; September 25: 추석; September 26: 추석. Taken from Korea Astronomy and Space Science Institute open data.
September 7: 백로; September 23: 추분. Computed from the sun's ecliptic longitude, not looked up in a table.
These dates hold for every visitor. A son-eomneun day is fixed by the lunar calendar alone and has nothing to do with your birth chart. What a given day means for you needs a birth date — there is no auspicious day that holds for everybody.