International Earth Rotation Service data. Initial slide ~2023-09-16, seismic ringdown ends 2023-09-25. Column 4 is length of day vs 86400 atomic seconds. tps://hpiers.obspm.fr/eop-pc/products/combined/C04.php?date=1&eop=3&year1=2023&month1=8&day1=1&year2=2023&month2=11&day2=1&SUBMIT=Submit+Search