| Description: The longitude_direction attribute identifies the direction of longitude (e.g. Positive East or Positive West) for a planet. The IAU definition for direction of positive longitude should be adopted: http://astrogeology.usgs.gov/groups/IAU-WGCCRE. Typically, for planets with prograde (direct) rotations, positive longitude direction is to the west. For planets with retrograde rotations, positive longitude direction is to the east. Generally the Positive West longitude_direction is used for planetographic systems and Positive East is used for planetocentric systems. If the data is defined with Spatial_Domain in a manner not recommended by the IAU, there is a optional Secondary_Spatial_Domain section to define a second set of bounding coordinates such that both Positive East and Positive West bounding coordinates can be provided. |
| Namespace Id: cart | Steward: img | Class Name: Geodetic_Model | Type: ASCII_Short_String_Collapsed |
| Minimum Value: None | Maximum Value: None | Minimum Characters: 1 | Maximum Characters: 255 |
| Unit of Measure Type: None | Default Unit Id: None | Attribute Concept: None | Conceptual Domain: SHORT_STRING |
| Status: Active | Nillable: false | Pattern: None |
| Permissible Value(s) | Value | Value Meaning |
| | Positive East | Positive East longitudes (i.e., longitudes measured positively to the east) will be used when the body's rotation is retrograde. Because of tradition, the Earth, Sun, and Moon do not conform with this definition. Their rotations are direct and longitudes run both east and west 180 degree, or east 360 degree. |
| | Positive West | Positive West longitudes (i.e., longitudes measured positively to the west) will be used when the rotation is prograde (direct). |