KPL/IK VIRTIS Instrument kernel =========================================================================== This instrument kernel (I-kernel) contains Venus Express VIRTIS optics, detector, and field-of-view parameters. Version and Date ======================================================================== Version 0.3 -- February 21, 2006. Boris Semenov, NAIF/JPL Changed center pixel for VIRTIS-M VIS and IR to 128.5. Version 0.2 -- January 18, 2006. Boris Semenov, NAIF/JPL Changed FOV definitions and descriptions to match updated frame layout, specifically: -- removed all data tagged with and all descriptions related to instrument IDs -248512 and -248514 -- added "full scan extent" FOV for ID -248510 Version 0.1 -- December 09, 2005. Jorge Diaz del Rio, RSSD/ESA Reference to URF frames deleted. Change of 'flight direction'. Venus Express flights in the +Y s/c direction. VIRTIS-H slit is along the +Y axis. Version 0.0 -- November 22, 2005. Jorge Diaz del Rio, RSSD/ESA Preliminary Version. Pending review from VIRTIS Team. References ======================================================================== 1. ``Kernel Pool Required Reading'', NAIF Document No.____ 2. ``C-kernel Required Reading'', NAIF Document No.____ 3. ``Rosetta - VIRTIS Experiment Interface Document Part-B'', ROS-EST-RS-3015/EID-B, Issue 2, February 14, 2000 4. Venus Express Frames Definition Kernel (FK), latest version. 5. ``VIRTIS: Experiment User Manual'', RO-VIR-UM-001, 2002-05-10 6. ``FM VIRTIS EXPERIMENT USER MANUAL (Delta Documentation)'', VVX-VIR-UM-001, Issue 1, June 05, 2004 Contact Information ======================================================================== Jorge Diaz del Rio, RSSD/ESA, (31) 71-565-5175, jdiaz@rssd.esa.int Boris Semenov, NAIF/JPL, (818) 354-8136, boris.semenov@jpl.nasa.gov 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 Venus Express instrument ID code, constructed using the spacecraft ID number (-248) followed by the NAIF three digit ID number for VIRTIS modules. These IDs are defined in [4] as follows: Instrument name ID -------------------- ------- VEX_VIRTIS -248500 VEX_VIRTIS-M -248510 VEX_VIRTIS-M_VIS -248511 VEX_VIRTIS-M_IR -248513 VEX_VIRTIS-H -248520 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 VIRTIS-M VIS optics is specified by INS-248511_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]: "VIRTIS description. To be copied from TBD source provided by the VIRTIS team." Mounting Alignment ======================================================================== Refer to the latest version of the Venus Express Frames Definition Kernel (FK) [4] for the VIRTIS reference frame definitions and mounting alignment information. Apparent FOV Layout ======================================================================== This diagram illustrates the VIRTIS-M VIS and IR apparent FOV layout for "zero" scan mirror position in the corresponding reference frame. These FOVs are associated with detector instrument IDs (-248511 and -248513). ^ +Xmvis (cross track) | +Xmir direction | | ---> of | ~0.014 degrees | flight | | v Pixel 1 | Pixel 256 --- +---------|---------+ | 1 line | x-------------> +Ymvis (along track) --- +-------------------+ +Ymir ^ 256 pixels/line | | ~3.67 degrees | |<----------------->| | | Boresight (+Z axis) is into the page This diagram illustrates the VIRTIS-M apparent FOV layout resulting from a full, 256 step, +/- 1.83 degree scan mirror sweep about Y axis. This FOV is associated with instrument ID -248510 and is useful only for rough coverage analysis as in reality the instrument does not always articulate the mirror over the whole possible range. ^ +Xm (cross track) | | Pixel 1,1 | direction --- *---------|---------+ ----> of ^ | | | flight | ~3.67 | | | | degrees | | | | | | | | 256 lines | x-------------> +Ym (along track) | (each for | | | a step in | | | scan seq.)| | V | | --- +-------------------+ | 256 pixels/line | ~3.67 degrees | |<----------------->| | | Boresight (+Z axis) is into the page This diagram illustrates the VIRTIS-H apparent FOV layout in the corresponding reference frame. ^ +Xh (cross track) | | | direction | ~0.0334 degrees | ----> of | | flight v Pixel 1 | Pixel 3 ------ +----|----+ | | x-------------> +Yh (along track) ------ +---------+ ^ 3 pixel/line | | | ~0.1 degrees ->|---------|<----- | | Boresight (+Z axis) is into the page Optical Parameters ======================================================================== The following VIRTIS-M VIS and IR and VIRTIS-H nominal first order optical parameters are included in the data section below, from [3]: ----------------------------------------------------------------- parameter VIRTIS-M/VIS VIRTIS-M/IR VIRTIS-H ----------------------------------------------------------------- Focal Length, mm 152.0 152.0 195.5 (*) f/ratio f/5.6 f/3.2 f/2.04 IFOV, rad/pixel Cross-track 0.00025 0.00025 0.000583 Along-track 0.00025 0.00025 0.000583 Field of view (deg) Cross-track 0.0143 0.0143 0.0334 Along-track 3.6669 3.6669 0.1002 Field of view (deg) - scan (**) Cross-track 3.6669 3.6669 n/a Along-track 3.6669 3.6669 n/a ----------------------------------------------------------------- (*) VIRTIS-H focal length was estimated from IFOV and pixel size. (**) This field of view corresponds to the maximum possible, using the complete 256 step scan sequence. 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-248511_FOCAL_LENGTH = ( 152.0 ) INS-248511_F/RATIO = ( 5.6 ) INS-248511_FOV_ANGULAR_SIZE = ( 0.000250, 0.064000 ) INS-248511_IFOV = ( 0.000250, 0.000250 ) INS-248513_FOCAL_LENGTH = ( 152.0 ) INS-248513_F/RATIO = ( 3.2 ) INS-248513_FOV_ANGULAR_SIZE = ( 0.000250, 0.064000 ) INS-248513_IFOV = ( 0.000250, 0.000250 ) INS-248520_FOCAL_LENGTH = ( 195.5 ) INS-248520_F/RATIO = ( 2.04 ) INS-248520_FOV_ANGULAR_SIZE = ( 0.000583, 0.001749 ) INS-248520_IFOV = ( 0.000583, 0.000583 ) \begintext Detector Parameters ======================================================================== The nominal VIRTIS detector parameters from [5] are: ----------------------------------------------------------------- parameter VIRTIS-M/VIS VIRTIS-M/IR VIRTIS-H ----------------------------------------------------------------- Detector Array Size/Physical Along-track 1024 436 436 Cross-track 512 270 270 Detector Array Size/Spatial Cross-track 1 1 1 Along-track 256 (1) 256 (2) 3 Detector Array Center/Spatial Cross-track 0.5 0.5 0.5 Along-track 128.5 128.5 1.5 Pixel Size, microns/Spatial Cross-track 38 (3) 38 38 Along-track 38 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-248511_PIXEL_SIZE = ( 38, 38 ) INS-248511_PIXEL_SAMPLES = ( 256 ) INS-248511_PIXEL_LINES = ( 1 ) INS-248511_CCD_CENTER = ( 128.5, 0.5 ) INS-248513_PIXEL_SIZE = ( 38, 38 ) INS-248513_PIXEL_SAMPLES = ( 256 ) INS-248513_PIXEL_LINES = ( 1 ) INS-248513_CCD_CENTER = ( 128.5, 0.5 ) INS-248520_PIXEL_SIZE = ( 38, 38 ) INS-248520_PIXEL_SAMPLES = ( 3 ) INS-248520_PIXEL_LINES = ( 1 ) INS-248520_CCD_CENTER = ( 1.5, 0.5 ) \begintext FOV Definitions ======================================================================== This section contains definitions for the VIRTIS FOVs. These definitions are provided in the format required by the SPICE (CSPICE) function GETFOV (getfov_c). The set of assignments in the data section below defines the VIRTIS-M VIS and IR non-scanning FOVs and VIRTIS-H FOV with respect to the corresponding frames to be a rectangles with the corners defined by the first and last pixels of the spatial, along-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-248511_FOV_FRAME = 'VEX_VIRTIS-M_VIS' INS-248511_FOV_SHAPE = 'RECTANGLE' INS-248511_BORESIGHT = ( 0.000000 0.000000 152.000000 ) INS-248511_FOV_CLASS_SPEC = 'ANGLES' INS-248511_FOV_REF_VECTOR = ( 1.000000 0.000000 0.000000 ) INS-248511_FOV_REF_ANGLE = ( 0.00716197 ) INS-248511_FOV_CROSS_ANGLE = ( 1.83346494 ) INS-248511_FOV_ANGLE_UNITS = 'DEGREES' INS-248513_FOV_FRAME = 'VEX_VIRTIS-M_IR' INS-248513_FOV_SHAPE = 'RECTANGLE' INS-248513_BORESIGHT = ( 0.000000 0.000000 152.000000 ) INS-248513_FOV_CLASS_SPEC = 'ANGLES' INS-248513_FOV_REF_VECTOR = ( 1.000000 0.000000 0.000000 ) INS-248513_FOV_REF_ANGLE = ( 0.00716197 ) INS-248513_FOV_CROSS_ANGLE = ( 1.83346494 ) INS-248513_FOV_ANGLE_UNITS = 'DEGREES' INS-248520_FOV_FRAME = 'VEX_VIRTIS-H' INS-248520_FOV_SHAPE = 'RECTANGLE' INS-248520_BORESIGHT = ( 0.000000 0.000000 195.500000 ) INS-248520_FOV_CLASS_SPEC = 'ANGLES' INS-248520_FOV_REF_VECTOR = ( 1.000000 0.000000 0.000000 ) INS-248520_FOV_REF_ANGLE = ( 0.01670172 ) INS-248520_FOV_CROSS_ANGLE = ( 0.05010516 ) INS-248520_FOV_ANGLE_UNITS = 'DEGREES' \begintext The set of assignments in the data section below defines the VIRTIS-M FOV resulting from a full, 256 step, +/- 1.83 degree scan mirror sweep about Y axis with respect to VIRTIS-M frame to be a rectangle with the corners defined by the first and last pixels of the spatial, along-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-248510_FOV_FRAME = 'VEX_VIRTIS-M' INS-248510_FOV_SHAPE = 'RECTANGLE' INS-248510_BORESIGHT = ( 0.000000 0.000000 152.000000 ) INS-248510_FOV_CLASS_SPEC = 'ANGLES' INS-248510_FOV_REF_VECTOR = ( 1.000000 0.000000 0.000000 ) INS-248510_FOV_REF_ANGLE = ( 1.83346494 ) INS-248510_FOV_CROSS_ANGLE = ( 1.83346494 ) INS-248510_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 VIRTIS components it is the spacecraft. \begindata INS-248500_PLATFORM_ID = ( -248000 ) INS-248510_PLATFORM_ID = ( -248000 ) INS-248511_PLATFORM_ID = ( -248000 ) INS-248513_PLATFORM_ID = ( -248000 ) INS-248520_PLATFORM_ID = ( -248000 ) \begintext