| Gb | Eng |
|---|---|
| 旋标装置飞机控制板上的指示器或观测仪，用来测量角度 | An indicator or a sighting apparatus on a plane table, used in angular measurement. |
| 天底天球上，在观测者垂直向下的一点，与天顶完全相对 | A point on the celestial sphere directly below the observer, diametrically opposite the zenith. |
| 蚀天体的部分或全部受到其他天体的遮掩而变得晦暗，这种现象与特定观测者相关 | The partial or complete obscuring, relative to a designated observer, of one celestial body by another. |