《宋史·志·卷一》
绍圣二年，清台因为赤道度数有差错，又命令考校订正。
绍圣二年，清台以赤道度数有差，复命考正。
In the second year of the Shaoxing Era, Qingtai discovered that there was an error in the equator's angle and therefore ordered a recalculation of its position.