Ha' K'in Xook yielded the throne on March 24, 780 AD (9.17.9.5.11 10 Chuwen 19 Sip) [REF].
Regardless, K'inich Yat Ahk II took up the throne on May 31, 781 AD (9.17.10.9.4 1 K'an 7 Yaxk'in), almost a year following the end of Ha' K'in Xook's reign.