| Description: The PDS3 name for this attribute was CSS:MIN_FOOTPRINT_SAMPLE (with MAP_PROJECTION_TYPE = EQUIRECTANGULAR), and was defined as "Minimum size of footprints along the sample axis". The meaning of this is unclear, but we believe it means the (angular) length along the horizontal direction of the smallest footprint (a CIRS detector) on the pixel grid, and have renamed it in PDS4 accordingly as equirectangular_min_footprint_width. The equirectangular projection is used for observations of Saturn and its satellites, but not for the rings. The sample coordinate is West longitude (in units of degrees), which decreases with increasing sample index, so that surface features appear correctly when the cube line/sample planes are displayed with sample index increasing from left to right. CAVEAT USOR: Several examples of CIRS cubes do not appear to correctly identify their min/max footprint width/heights. For example, some using equirectangular projection list their max footprint width as 360 deg, even when there is no wrapping. |