KPL/IK VIR Instrument kernel =========================================================================== This instrument kernel (I-kernel) contains Dawn VIR optics, detector, and field-of-view parameters. Version and Date --------------------------------------------------------------------------- Version 0.1 -- May 9, 2005 -- Boris Semenov, NAIF/JPL Added radiator FOV. Version 0.0 -- October 12, 2004 -- Boris Semenov, NAIF/JPL Initial release. References --------------------------------------------------------------------------- 1. ``Kernel Pool Required Reading'' 2. ``C-kernel Required Reading'' 3. VIR ICD/MICD, latest version as of 10/12/04 4. Dawn Frames Definition Kernel (FK), latest version. 5. VIR CDR Presentations 6. Rosetta VIRTIS Documentation (ROS-EST-RS-30015/EID B and RO-VIR-UM-001) 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. Conventions for Specifying Data -------------------------------------------------------- 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 Dawn instrument ID code, constructed using the spacecraft ID number (-226) followed by the NAIF three digit ID number for VIR module. These IDs are defined in [4] as follows: Instrument name ID -------------------- ------- DAWN_VIR -203200 DAWN_VIR_VIS -203211 DAWN_VIR_VIS_SCAN -203212 (*) DAWN_VIR_IR -203213 DAWN_VIR_IR_SCAN -203214 (*) DAWN_VIR_RAD -203209 (*) _SCAN names/IDs are defined to allow specifying a complete FOV resulting from side scan the VIR scan mirror. 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 VIR VIS optics is specified by INS-203211_FOCAL_LENGTH The upper bound on the length of all keywords is 32 characters. If a keyword is included in more than one file, or if the same keyword appears more than once within a single file, the last assignment supersedes any earlier assignments. Overview -------------------------------------------------------- From [TBD]: TBD Mounting Alignment -------------------------------------------------------- Refer to the latest version of the Dawn Frames Definition Kernel (FK) [4] for the VIR reference frame definitions and mounting alignment information. Apparent FOV Layout -------------------------------------------------------- WARNING --- the description/diagram below have not been verified This diagram illustrates the VIR apparent FOV layout for "zero" scan mirror position in the corresponding reference frame. ^ | direction of | flight | ^ +Xvis (along track) | +Xir | | | ~0.014 degrees | | | v Pixel 1 | Pixel 256 --- +---------|---------+ | 1 line | x-------------> +Yvis (cross track) --- +-------------------+ +Yir ^ 256 pixels/line | | ~3.67 degrees | |<----------------->| | | Boresight (+Z axis) is into the page This diagram illustrates the VIR apparent FOV layout resulting from a full, 256 step, +/- 1.83 degree scan mirror sweep about Y axis. ^ | direction of | flight | ^ +Xvis (along track) | +Xir | Pixel 1,1 | --- *---------|---------+ ^ | | | | ~3.67 | | | | degrees | | | | | | | | 256 lines | x-------------> +Yvis (cross track) | (each for | | +Yir | a step in | | | scan seq.)| | V | | --- +-------------------+ | 256 pixels/line | ~3.67 degrees | |<----------------->| | | Boresight (+Z axis) is into the page Optical Parameters -------------------------------------------------------- The following VIR VIS and IR nominal first order optical parameters are included in the data section below, from [6]: ----------------------------------------------------------------- parameter VIR/VIS VIR/IR ----------------------------------------------------------------- Focal Length, mm 152.0 152.0 f/ratio f/5.6 f/3.2 IFOV, rad/pixel Cross-track 0.00025 0.00025 Along-track 0.00025 0.00025 Field of view (deg) Cross-track 3.6669 3.6669 Along-track 0.0143 0.0143 Field of view (deg) - scan Cross-track 3.6669 3.6669 Along-track 3.6669 3.6669 ----------------------------------------------------------------- The keywords below provide nominal values from the table above. Angular size values in the keywords are given radians, with the cross-track size being the first value and the along-track size being the second value in each pair. \begindata INS-203211_FOCAL_LENGTH = ( 152.0 ) INS-203211_F/RATIO = ( 5.6 ) INS-203211_FOV_ANGULAR_SIZE = ( 0.064000, 0.000250 ) INS-203211_IFOV = ( 0.000250, 0.000250 ) INS-203213_FOCAL_LENGTH = ( 152.0 ) INS-203213_F/RATIO = ( 3.2 ) INS-203213_FOV_ANGULAR_SIZE = ( 0.064000, 0.000250 ) INS-203213_IFOV = ( 0.000250, 0.000250 ) \begintext Detector Parameters -------------------------------------------------------- The nominal VIR detector parameters from [6] are: ----------------------------------------------------------------- parameter VIR/VIS VIR/IR ----------------------------------------------------------------- Detector Array Size/Physical Cross-track 508 270 Along-track 1024 436 Detector Array Size/Spatial Cross-track 256 (1) 256 (2) Along-track 1 1 Detector Array Center/Spatial Cross-track 127.5 127.5 Along-track 0.5 0.5 Pixel Size, microns/Spatial Cross-track 38 (3) 38 Along-track 38 38 ----------------------------------------------------------------- (1) VIS CCD pixels are 2x2 binned at detector level (2) assuming IR reads out the same number of pixels as VIS (3) size of a 2x2 binned pixel The values are given in microns for PIXEL_SIZE keywords and in counts for PIXEL_SAMPLES, PIXEL_LINES, and CENTER keywords. \begindata INS-203211_PIXEL_SIZE = ( 38, 38 ) INS-203211_PIXEL_SAMPLES = ( 256 ) INS-203211_PIXEL_LINES = ( 1 ) INS-203211_CCD_CENTER = ( 127.5, 0.5 ) INS-203213_PIXEL_SIZE = ( 38, 38 ) INS-203213_PIXEL_SAMPLES = ( 256 ) INS-203213_PIXEL_LINES = ( 1 ) INS-203213_CCD_CENTER = ( 127.5, 0.5 ) \begintext FOV Definitions --------------------------------------------------------------------------- This section contains definitions for the VIR FOVs. These definitions are provided in a format required by the SPICE (CSPICE) function GETFOV (getfov_c). The set of assignments in the data section below defines the VIR VIS and IR non-scanning FOVs with respect to the corresponding frames to be a rectangles with the corners defined by the first and last pixels of the spatial, cross-track line and the boresight along the +Z axis. These FOV definitions use angular extent style specification with the cross and along track angular sizes taken from the ``Optics Parameters'' section above. \begindata INS-203211_FOV_FRAME = 'DAWN_VIR_VIS' INS-203211_FOV_SHAPE = 'RECTANGLE' INS-203211_BORESIGHT = ( 0.000000 0.000000 152.000000 ) INS-203211_FOV_CLASS_SPEC = 'ANGLES' INS-203211_FOV_REF_VECTOR = ( 1.000000 0.000000 0.000000 ) INS-203211_FOV_REF_ANGLE = ( 0.00716197 ) INS-203211_FOV_CROSS_ANGLE = ( 1.83346494 ) INS-203211_FOV_ANGLE_UNITS = 'DEGREES' INS-203213_FOV_FRAME = 'DAWN_VIR_IR' INS-203213_FOV_SHAPE = 'RECTANGLE' INS-203213_BORESIGHT = ( 0.000000 0.000000 152.000000 ) INS-203213_FOV_CLASS_SPEC = 'ANGLES' INS-203213_FOV_REF_VECTOR = ( 1.000000 0.000000 0.000000 ) INS-203213_FOV_REF_ANGLE = ( 0.00716197 ) INS-203213_FOV_CROSS_ANGLE = ( 1.83346494 ) INS-203213_FOV_ANGLE_UNITS = 'DEGREES' \begintext The set of assignments in the data section below defines the VIR VIS and IR apparent FOVs resulting from a full, 256 step, +/- 1.83 degree scan mirror sweep about Y axis with respect to the corresponding frames to be a rectangles with the corners defined by the first and last pixels of the spatial, cross-track line in the first and last scan positions and the boresight along the +Z axis. These FOV definitions use angular extent style specification with the cross and along track angular sizes taken from the ``Optics Parameters'' section above. \begindata INS-203212_FOV_FRAME = 'DAWN_VIR_VIS' INS-203212_FOV_SHAPE = 'RECTANGLE' INS-203212_BORESIGHT = ( 0.000000 0.000000 152.000000 ) INS-203212_FOV_CLASS_SPEC = 'ANGLES' INS-203212_FOV_REF_VECTOR = ( 1.000000 0.000000 0.000000 ) INS-203212_FOV_REF_ANGLE = ( 1.83346494 ) INS-203212_FOV_CROSS_ANGLE = ( 1.83346494 ) INS-203212_FOV_ANGLE_UNITS = 'DEGREES' INS-203214_FOV_FRAME = 'DAWN_VIR_IR' INS-203214_FOV_SHAPE = 'RECTANGLE' INS-203214_BORESIGHT = ( 0.000000 0.000000 152.000000 ) INS-203214_FOV_CLASS_SPEC = 'ANGLES' INS-203214_FOV_REF_VECTOR = ( 1.000000 0.000000 0.000000 ) INS-203214_FOV_REF_ANGLE = ( 1.83346494 ) INS-203214_FOV_CROSS_ANGLE = ( 1.83346494 ) INS-203214_FOV_ANGLE_UNITS = 'DEGREES' \begintext Radiator Sun Avoidance FOV Definition -------------------------------------------------------- Sun avoidance for VIR radiator is 175 degree cone centerered on spacecraft -X axis [3]. \begindata INS-203209_FOV_FRAME = 'DAWN_SPACECRAFT' INS-203209_FOV_SHAPE = 'CIRCLE' INS-203209_BORESIGHT = ( -1.000000 0.000000 0.000000 ) INS-203209_FOV_CLASS_SPEC = 'ANGLES' INS-203209_FOV_REF_VECTOR = ( 0.000000 1.000000 0.000000 ) INS-203209_FOV_REF_ANGLE = ( 87.5 ) INS-203209_FOV_ANGLE_UNITS = 'DEGREES' \begintext Optical Distortion -------------------------------------------------------- [TBD] Platform ID --------------------------------------------------------------------------- This number is the NAIF instrument ID of the platform on which the instrument mounted. All VIR components it is the spacecraft. \begindata INS-226200_PLATFORM_ID = ( -226000 ) INS-203211_PLATFORM_ID = ( -226000 ) INS-203213_PLATFORM_ID = ( -226000 ) \begintext