《史记·八书·天官书》
岁星运行失次有如下情况：进而向东北行，不出三月就会出现天棓星，天棓星长约四丈，末端尖锐。
其失次舍以下，进而东北，三月生天棓，长四丈，末兑。
When the orbit of Jupiter is shifted off its course, there are the following conditions: If it moves forward into the northeast, within three months, the Tianchen (天棓) celestial body will appear. Tianchen is approximately four zhang in length, and has a sharp point at its end.