PDS_VERSION_ID = 3 RECORD_TYPE = STREAM RELEASE_ID = 0001 REVISION_ID = 0000 OBJECT = TEXT PUBLICATION_DATE = 2004-09-29 NOTE = "Description of the geometrical data cubes content." END_OBJECT = TEXT END GEOMETRICAL DATA CUBES CONTENT The auxiliary cube is coded as 32 bits signed integer (LSB). It has the same structure as the science data cube (Sample, Band, Line). -- 1st dimension : length of the scan (16, 32, 64 or 128 pixels) -- 2nd dimension : 51 parameters describing the observation geometry -- 3rd dimension : rank of the scan The first and third dimensions are the same as that of the corresponding science level-1b data cube. From geometry planes, one value of the corresponding parameter is associated to each of the spectra in the science level-1b data cubes. Howevre, this is an exception with the second plane, which is used to store information on the time at the beginning of the IR scan (13 values, identical to that of the corresponding scan in the science level-1b data cube). All angles are expressed in units of 0.0001°, all distances are expressed in meters. For the SCET time, both seconds and microseconds are coded as a MSW (16 bits) and a LSW (16 bits) in distinct 32 bits words, so as to maintain consistency with the science data cube. _____________________ ^ / /| / / / | scan / / / | pixels / / / | / / / | 51 parameters (planes) / | ------------> / | /____________________/ | | | | | | | | | | | | | | | | rank | | | / of the | | | / scan | | | / | | | / v | | / | | / | |/ |____________________/ Plane Parameter Unit ----- ------------------------------------------------------------------- -------------- 1 IR scan mirror position DIMENSIONLESS 2 time at the beginning of the IR scan (1) 3 incidence angle w.r.t the outward normal to the reference ellipsoid 0.0001 4 emergence angle w.r.t the outward normal to the reference ellipsoid 0.0001 5 incidence angle w.r.t the opposite direction of the center of Mars 0.0001 6 emergence angle w.r.t the opposite direction of the center of Mars 0.0001 7 longitude of the pixel footprint center point 0.0001 8 latitude of the pixel footprint center point 0.0001 9 incidence angle w.r.t the local normal (2) 0.0001 10 emergence angle w.r.t the local normal (2) 0.0001 11 phase angle w.r.t the local normal (2) 0.0001 12 slant distance from the spacecraft to pixel footprint center point 13 elevation of the pixel footprint center point (2) 14-17 longitude of the 4 pixel footprint corner points 0.0001 18-21 latitude of the 4 pixel footprint corner points 0.0001 22-36 same information as plane 7-21 for SWIR-L channel 37-51 same information as plane 7-21 for VNIR channel (1) UT -- year, month, day, hour, minute, second, millisecond (7 values) OBT -- seconds, milliseconds (2 values) SCET -- seconds (2 values), microseconds (2 values) (2) In the case of limb observations, incidence and emergence angles (planes number 9, 10, 24, 25, 39, and 40) are computed with respect to the opposite direction of the center of Mars instead of using local topography. Also, planes number 13, 28, and 43 are replaced with the altitude of the central tangent point above the surface of Mars, plus an offset equal to 65536. (3) Planes from 3 to 21 are related to the SWIR-C channel.