884 days, I calculated the dates backward to see if there was any possible date on which a conjunction and a solar term both occurring at midnight that would result in the times of solar terms close to those of the Zhuanxu calendar. I found a possible epoch. It's at the time when J5 and conjunction were assumed to both occur at midnight on June 12, 6297 BCE (Julian day = <span class="nowrap">-578393.5</span>). The solar terms computed using this epoch are about 10 minutes earlier than those in the Zhuanxu c