| Description: Provides the ordinary longitude coordinate of the origin (oblique latitude = oblique longitude = 0) for the oblique coordinate system used to specify the Oblique Cylindrical projection, for example, as used in Cassini BIDR (basic image data record). Note that whereas some past PDS products may utilize oblique projections defined solely in terms of the reference_latitude and reference_longitude (i.e., with a third defining angle always set to zero), the Cassini BIDRs require the full generality of three nonzero rotation angles. These angles are represented by the keywords oblique_proj_pole_latitude, oblique_proj_pole_longitude, and oblique_proj_pole_rotation. The values of reference_latitude and reference_longitude are consistent with the latter three angles but do not uniquely define the oblique coordinate system on their own. |