KPL/IK OMEGA Instrument kernel ======================================================================== This instrument kernel (I-kernel) contains Mars Express OMEGA Visible and Near InfraRed (VNIR) and Short Wavelength InfraRed (SWIR) Short wavelength (SWIR-C) and Long wavelength (SWIR-L) channel optics, detector, and field-of-view parameters. Version and Date ----------------------------------------------------------------------------- Version 0.3 -- March 23, 2021 -- Ricardo Valles Blanco, ESAC/ESA Corrected typos and updated contact information for Mars Express PDS3 V2.0 release. Version 0.2 -- March 13, 2020 -- Marc Costa Sitja, ESAC/ESA Minor edits to the Instrument Kernel. Updated information as provided by OMEGA Instrument team. Version 0.1 -- September 7, 2004 -- Nicolas Manaud, IAS First delivery to PSA. Version 0.0 -- May 19, 2003 -- Boris Semenov, NAIF/JPL Just a skeleton with a whole bunch of empty space to be filled in. References ----------------------------------------------------------------------------- 1. ``Kernel Pool Required Reading'' 2. ``C-kernel Required Reading'' 3. ``OMEGA PID-B'', OME-CI-0022-003-IAS, February 25, 2000 4. Mars Express Frames Definition Kernel (FK), latest version. Contact Information ----------------------------------------------------------------------------- If you have any questions regarding this file contact SPICE support at ESAC: Alfredo Escalante Lopez (+34) 91-8131-429 spice@sciops.esa.int, or NAIF at JPL: Boris Semenov (818) 354-8136 Boris.Semenov@jpl.nasa.gov or the OMEGA instrument team at IAS/CNRS: Yves Langevin, IAS/CNRS, (+33) 169 858 681 yves.langevin@ias.u-psud.fr Implementation Notes ----------------------------------------------------------------------------- Applications that need SPICE I-kernel data must ``load'' the I-kernel file, normally during program initialization. Loading the kernel using the SPICELIB routine FURNSH causes the data items and their associated values present in the kernel to become associated with a data structure called the ``kernel pool''. The application program may then obtain the value(s) for any IK data item using the SPICELIB routines GDPOOL, GIPOOL, GCPOOL. Routine GETFOV may be used if the file contains instrument field-of-view (FOV) specification. See [1] for details. This file was created with, and can be updated with a text editor or word processor. Naming Conventions ----------------------------------------------------------------------------- Data items are specified using ``keyword=value'' assignments [1]. All keywords referencing values in this I-kernel start with the characters `INS' followed by the NAIF MEX instrument ID code, constructed using the spacecraft ID number (-41) followed by the NAIF three digit ID number for OMEGA VNIR (410), SWIR-C (421), or SWIR-L (422) channel. These IDs are defined in [4] as follows: Instrument name ID -------------------- ------ MEX_OMEGA -41400 MEX_OMEGA_VNIR -41410 MEX_OMEGA_SWIR -41420 MEX_OMEGA_SWIR_C -41421 MEX_OMEGA_SWIR_L -41422 The remainder of the keyword is an underscore character followed by the unique name of the data item. For example, the focal length of the OMEGA VNIR channel optics is specified by INS-41410_FOCAL_LENGTH The upper bound on the length of all keywords is 32 characters. If a keyword is included in more then one file, or if the keyword appears more than once within a single file, the last assignment supersedes any earlier assignments. Overview ----------------------------------------------------------------------------- OMEGA is a mapping spectrometer working both in the visible and near infrared spectral ranges. It is made of two grating spectrographs, one working in the 0.35 to 1 um visible and near infrared range (VNIR channel), the other in the 1 to 5.2 um short wavelength infrared range (SWIR channel). The visible channel works in pushbroom mode, using a Thomson CCD matrix 384 x 288 pixels (spatial x spectral). The spectrum of a given point of the observed target is formed along a column of the array while spatial resolution along the spectrograph slit is obtained along the lines. The motion of the satellite gives the second spatial dimension itself, the spectrograph slit being oriented perpendicularly to the spacecraft track. In such a case the "elementary exposure" provides the full spectra of every spatial pixel along the slit. The displacement of the spacecraft with respect to the target surface during the "elementary exposure time" must be comparable to (or smaller than) the expected spatial resolution, corresponding to the pixel size. The SWIR channel, working in whiskbroom mode, is equipped with two InSb linear arrays of 128 elements each, cooled down to 70K approximately and multiplexed by a charge transfer device. The spectrum of a given point of the observed target is formed on the linear detectors array. The spatial images are obtained sequentially by combining the movement of a scanning mirror in front of the instrument and the spacecraft displacement. The typical integration time, defined by the movement of the satellite relative to the ground and the spatial resolution expected, is 5 msec. Optical Parameters ----------------------------------------------------------------------------- The following OMEGA VNIR and SWIR optical parameters are included in the data section below, taken from [3]: ----------------------------------------------------------------- parameter VNIR SWIR-C SWIR-L ----------------------------------------------------------------- Focal Length, mm 57.6 200.0 200.0 f/ratio 3.7 4 4 IFOV, mrad/pixel 0.4 (a) 1.2 1.2 Field of view (rad) Cross-track 0.1536 (b) 0.1536 (c) 0.1536 (c) Along-track 0.0004 0.0012 0.0012 ----------------------------------------------------------------- (a) "physical" pixel IFOV; in the nominal mapping mode VNIR channel is operated in 3x3 summing mode providing effective pixel IFOV of 1.2 mrad/pixel (b) for full 384 pixel by 0.4 mrad/pixel FOV; same for the nominal mapping mode -- 128 (3x3)pixels by 1.2 mrad/(3x3)pixel (c) cross-track FOV is achieved by scanning mirror; the number provided in the table corresponds to the nominal mapping mode scanning range of +- 4.4 degrees; FOV Definitions ----------------------------------------------------------------------------- The parameters provided in this file can be considered as valid within error margins. At the OMEGA scale (IFOV 1 mrad, 300 m/pixel at pericenter), the AGKE (Absolute Guidance Knowledge Error) dominates the error budget as an error ellipse elongated along-track is a signature of guidance errors. (WARNING: FOV DEFINITIONS BELOW ARE DEFINED FOR 8.8 DEGREE 1-PIXEL-WIDE 3X3-SUMMED VNIR PUSH BROOM LINE AND A SINGLE PIXEL WISKBROOM FOR SWIR-C/L.) This section contains definitions for the OMEGA VNIR, SWIR-C and SWIR-L FOVs. These definitions are provided in a format required by the SPICE (CSPICE) function GETFOV (getfov_c). VNIR Channel ~~~~~~~~~~~~ \begindata INS-41410_FOV_FRAME = 'MEX_OMEGA_VNIR' INS-41410_FOV_SHAPE = 'RECTANGLE' INS-41410_BORESIGHT = ( 0.00000 0.00000 1.00000 ) INS-41410_FOV_CLASS_SPEC = 'ANGLES' INS-41410_FOV_REF_VECTOR = ( 1.00000 0.00000 0.00000 ) INS-41410_FOV_REF_ANGLE = 2.06 INS-41410_FOV_CROSS_ANGLE = 2.06 INS-41410_FOV_ANGLE_UNITS = 'ARCMINUTES' \begintext SWIR-C and SWIR-L Channels ~~~~~~~~~~~~~~~~~~~~~~~~~~ \begindata INS-41421_FOV_FRAME = 'MEX_OMEGA_SWIR_C' INS-41421_FOV_SHAPE = 'RECTANGLE' INS-41421_BORESIGHT = ( 0.00000 0.00000 1.00000 ) INS-41421_FOV_CLASS_SPEC = 'ANGLES' INS-41421_FOV_REF_VECTOR = ( 1.00000 0.00000 0.00000 ) INS-41421_FOV_REF_ANGLE = 2.075 INS-41421_FOV_CROSS_ANGLE = 2.075 INS-41421_FOV_ANGLE_UNITS = 'ARCMINUTES' INS-41422_FOV_FRAME = 'MEX_OMEGA_SWIR_L' INS-41422_FOV_SHAPE = 'RECTANGLE' INS-41422_BORESIGHT = ( 0.00000 0.00000 1.00000 ) INS-41422_FOV_CLASS_SPEC = 'ANGLES' INS-41422_FOV_REF_VECTOR = ( 1.00000 0.00000 0.00000 ) INS-41422_FOV_REF_ANGLE = 2.075 INS-41422_FOV_CROSS_ANGLE = 2.075 INS-41422_FOV_ANGLE_UNITS = 'ARCMINUTES' \begintext OMEGA Pixels Geometry ----------------------------------------------------------------------------- This section provides some information on how to compute the components of each OMEGA pixel pointing vector with respect to the spacecraft mechanical frame. Each pixel pointing vectors are defined by rotating the "central" pixel vector about the +Y axis of the SWIR-C detector by an offset angle given the position of the scanning mirror We call "central" pixel of a detector the pixel pointing towards the +Z axis of its own detector frame (as defined above). In-flight geometrical calibration allowed to measure detectors mounting alignment values (available in the latest version the MEX Frame Kernel [4]) so you can compute transform vector coordinates from any detector frames to the SWIR-C detector frame and/or to the spacecraft mechanical frame. The following parameters describe the scanning mirror motion. For a given mirror position expressed in digital number (available within OMEGA level-1b science data qubes), we can calculate the offset angle, in degrees, as follows: offset_angle = ( dn_position - CENTER_POSITION ) * SLOPE Scanning mirror motion ----------------------------------------------------------------------------- TIME_STEP, expressed in seconds, is used to determine as accurate as possible the time of pixels signal acquisition. Indeed, the science data qubes contain the time at the beginning of each IR scan. \begindata INS-41420_MIRROR_TIME_STEP = 0.005 INS-41420_MIRROR_CENTER_POSITION = 512 INS-41420_MIRROR_SLOPE = 0.0092243187 \begintext VNIR Channel Optical distorsion ----------------------------------------------------------------------------- The following 128-elements array contains the position of the visible detector pixels, expressed in terms of double-precision mirror step unit, with respect to the SWIR-C frame. \begindata INS-41410_PIXEL_DN= ( 70.01791 78.26182 86.23585 92.27941 99.62275 107.48679 114.98441 122.86058 130.26586 137.62265 145.25873 153.32201 161.17167 168.86978 176.51916 184.39024 192.18049 199.71733 207.39576 215.01479 221.55824 230.11459 237.31123 244.37572 251.89502 259.32616 266.89602 274.25663 281.91641 289.28983 296.39376 303.94111 311.51020 318.74974 325.93419 333.04188 340.75677 347.76456 354.78212 361.86722 368.85536 376.36713 383.01728 389.89619 397.15219 404.32303 411.24001 418.57173 425.37073 432.39295 439.51515 446.75659 453.71281 460.71058 467.92458 474.67274 482.14579 488.84036 496.27281 503.08683 510.51960 517.30773 524.05372 531.45836 538.31183 545.05699 552.47404 559.28009 565.99943 573.30513 580.16339 586.91602 593.80111 601.14220 607.82651 614.51986 621.69898 628.71967 635.37857 642.75543 649.61134 657.07658 663.87386 671.42158 678.89524 686.06807 693.21933 700.78666 708.23036 715.17945 722.60685 730.18503 737.72732 744.93886 752.15496 759.85919 767.21381 774.42656 781.64245 789.17820 796.92040 804.07865 811.27865 819.09723 826.59971 833.59910 841.37062 848.77660 856.47193 864.08056 871.52453 879.09326 887.25745 895.34048 902.79447 910.93214 919.18961 927.22130 935.42327 944.00981 952.87840 960.74387 969.73205 978.94337 987.13999 996.34754 1005.29942 1014.40741 ) \begintext Platform ID ----------------------------------------------------------------------------- This number is the NAIF instrument ID of the platform on which the cameras are mounted. For OMEGA the platform is the spacecraft. \begindata INS-41410_PLATFORM_ID = ( -41000 ) INS-41421_PLATFORM_ID = ( -41000 ) INS-41422_PLATFORM_ID = ( -41000 ) \begintext End of IK file.