| Name | Description |
|---|---|
| East | Unit vector in the local horizontal plane pointing east. |
| Moon | Apparent position of the Moon center as seen from the object's center. |
| Moonlight | Apparent direction from which moonlight arrives at the object's location. |
| Nadir(Detic) | Unit vector pointing opposite to the surface normal. |
| North | Unit vector in the local horizontal plane pointing north. |
| Position | True position of the object's center with respect to its central body center. |
| South | Unit vector in the local horizontal plane pointing south. |
| Sun | Apparent direction from which sunlight arrives at the object's location. |
| Sunlight | Apparent direction from which sunlight arrives at the object's location. |
| West | Unit vector in the local horizontal plane pointing west. |
| Zenith(Centric) | Unit vector along the direction from the center of the central body to the object. |
| Zenith(Detic) | Unit vector pointing along the surface normal. |
STK Programming Interface 11.0.1