KPL/IK SRU Instrument Kernel ============================================================================== This instrument kernel (I-kernel) contains references to the mounting alignment, internal and FOV geometry for the Cassini Stellar Reference Unit (SRU) detectors. Version and Date ---------------------------------------------------------- The TEXT_KERNEL_ID stores version information of loaded project text kernels. Each entry associated with the keyword is a string that consists of four parts: the kernel name, version, entry date, and type. For example, the ISS I-kernel might have an entry as follows: TEXT_KERNEL_ID += 'CASSINI_ISS V0.0.0 29-SEPTEMBER-1999 IK' | | | | | | | | KERNEL NAME <-------+ | | | | | V VERSION <-------+ | KERNEL TYPE | V ENTRY DATE SRU I-Kernel Version: \begindata TEXT_KERNEL_ID += 'CASSINI_SRU V0.2.0 17-SEPTEMBER-2003 IK' \begintext Version 0.2 -- September 17, 2003 -- Lee Elson -- Corrected several documentation typos. Version 0.1 -- April 23, 2001 -- Scott Turner -- Updated kernel to utilize new FOV ANGLES specification. Version 0.0 -- March 12, 2001 -- Scott Turner -- Initial Prototype Release for Review. References ---------------------------------------------------------- 1. ``Cassini Science Instruments and Investigations'', Revised Second Printing. Stephen J. Edberg. 2. ``Kernel Pool Required Reading'' 3. <> 4. Cassini/NAIF SPICE Workship, November 8-9, 1999. 5. Cassini Spacecraft Frames Definition Kernel 6. Cassini Spacecraft Attitude and Articulation Control Subsystem Interface Control Document (JPL:D-12463, PD:699-113) Contact Information ---------------------------------------------------------- Direct questions, comments or concerns about the contents of this kernel to: Lee Elson, NAIF/JPL, (818)-354-4223, Lee.Elson@jpl.nasa.gov Implementation Notes ---------------------------------------------------------- This file is used by the SPICE system as follows: programs that make use of this instrument kernel must ``load'' the kernel, normally during program initialization. Loading the kernel associates data items with their names in a data structure called the ``kernel pool''. The SPICELIB routine FURNSH and CSPICE routine furnsh_c load SPICE kernels as shown below: FORTRAN (SPICELIB) CALL FURNSH ( 'kernel_name' ) C (CSPICE) furnsh_c ( "kernel_name" ) In order for a program or subroutine to extract data from the pool, the SPICELIB routines GDPOOL and GIPOOL are used. See [2] for details. This file was created and may be updated with a text editor or word processor. Naming Conventions ---------------------------------------------------------- All names referencing values in this I-kernel start with the characters `INS' followed by the NAIF Cassini spacecraft ID number (-82) followed by a NAIF three digit code for the SRU detectors. (SRU-A = 001, SRU-B = 002, SRU-A_RAD = 008, SRU-B_RAD = 009). The remainder of the name is an underscore character followed by the unique name of the data item. For example, the SRU boresight direction in the SRU frame (``CASSINI_SRU-A'' -- see [5] ) is specified by: INS-82001_BORESIGHT The upper bound on the length of the name of any data item is 32 characters. If the same item is included in more than one file, or if the same item appears more than once within a single file, the latest value supersedes any earlier values. SRU description ---------------------------------------------------------- From [3]: Awaiting high-level descriptive information reference document. SRU Field of View Parameters ---------------------------------------------------------- The field of view parameters for the two focal planes that constitute the SRU detectors are: -- Stellar Reference Unit-A (SRU-A) -- Stellar Reference Unit-B (SRU-B) Rectangular FOVs: -------------- --------------------- --------------------- Detector Horizontal Vertical -------------- --------------------- --------------------- SRU-A 15.0 degrees 15.0 degrees SRU-B 15.0 degrees 15.0 degrees -------------- --------------------- --------------------- The keywords INS[ID]_FOV_FRAME, INS[ID]_FOV_SHAPE, INS[ID]_BORESIGHT, and FOV ANGLES specification keywords defined below are used to describe the instrument field of view. Since the fields of view are rectangular, the INS[ID]_FOV_SHAPE will be 'RECTANGLE'. GETFOV returns four vectors. All FOV boresights lie along the Z-axis. Stellar Reference Unit-A (SRU-A) FOV Definition SRU-A possesses a rectangular field of view, so four boundary corner vectors require visualization. First consider looking down the X-axis in the CASSINI_SRU-A frame at the X=0 plane. This permits the computation of the Y components of the boundary corner vectors. In this plane the half angle of note is 7.5 degrees. (Note we are arbitrarily choosing a vector that terminates in the Z=1 plane.) ^ Y | ins | | /| | / | | / | | / o | |/ 7.5 | x---------------> X \ | Z ins \ | ins \ | \ | \| |-- 1.0 --| Plane X = 0 Now from here we see that the Y component of one boundary corner vector is: Y Component = +/- 1.0 * tan ( 7.5 degrees ) = +/- 0.131652498 Since the field of view is square, precisely the same computation holds for the X components. Utilizing the ANGLES FOV specification: Stellar Reference Unit-A (SRU-A): \begindata INS-82001_FOV_FRAME = 'CASSINI_SRU-A' INS-82001_FOV_SHAPE = 'RECTANGLE' INS-82001_BORESIGHT = ( 0.0000000000000000 0.0000000000000000 +1.0000000000000000 ) INS-82001_FOV_CLASS_SPEC = 'ANGLES' INS-82001_FOV_REF_VECTOR = ( 0.0000000000000000 +1.0000000000000000 0.0000000000000000 ) INS-82001_FOV_REF_ANGLE = ( 7.5 ) INS-82001_FOV_CROSS_ANGLE = ( 7.5 ) INS-82001_FOV_ANGLE_UNITS = 'DEGREES' \begintext Stellar Reference Unit-B (SRU-B) FOV Definition SRU-B is identical to SRU-A. It too possesses a rectangular field of view, so four boundary corner vectors require visualization. As before consider looking down the X-axis in the CASSINI_SRU-B frame at the X=0 plane. This permits the computation of the Y components of the boundary corner vectors. In this plane the half angle of note is 7.5 degrees. (Note we are arbitrarily choosing a vector that terminates in the Z=1 plane.) ^ Y | ins | | /| | / | | / | | / o | |/ 7.5 | x---------------> X \ | Z ins \ | ins \ | \ | \| |-- 1.0 --| Plane X = 0 Now from here we see that the Y component of one boundary corner vector is: Y Component = +/- 1.0 * tan ( 7.5 degrees ) = +/- 0.131652498 Since the field of view is square, precisely the same computation holds for the X components. Utilizing the ANGLES FOV specification: Stellar Reference Unit-B (SRU-B): \begindata INS-82002_FOV_FRAME = 'CASSINI_SRU-B' INS-82002_FOV_SHAPE = 'RECTANGLE' INS-82002_BORESIGHT = ( 0.0000000000000000 0.0000000000000000 +1.0000000000000000 ) INS-82002_FOV_CLASS_SPEC = 'ANGLES' INS-82002_FOV_REF_VECTOR = ( 0.0000000000000000 +1.0000000000000000 0.0000000000000000 ) INS-82002_FOV_REF_ANGLE = ( 7.5 ) INS-82002_FOV_CROSS_ANGLE = ( 7.5 ) INS-82002_FOV_ANGLE_UNITS = 'DEGREES' \begintext The FOV values for the SRU radiators are place holders until a time when the real values are provided. SRU-A Radiator (SRU-A_RAD): \begindata INS-82008_FOV_FRAME = 'CASSINI_SRU-A_RAD' INS-82008_FOV_SHAPE = 'CIRCLE' INS-82008_BORESIGHT = ( 0.0000000000000000 0.0000000000000000 +1.0000000000000000 ) INS-82008_FOV_CLASS_SPEC = 'ANGLES' INS-82008_FOV_REF_VECTOR = ( +1.0000000000000000 0.0000000000000000 +0.0000000000000000 ) INS-82008_FOV_REF_ANGLE = ( 90.0 ) INS-82008_FOV_ANGLE_UNITS = 'DEGREES' \begintext SRU-B Radiator (SRU-B_RAD): \begindata INS-82009_FOV_FRAME = 'CASSINI_SRU-B_RAD' INS-82009_FOV_SHAPE = 'CIRCLE' INS-82009_BORESIGHT = ( 0.0000000000000000 0.0000000000000000 +1.0000000000000000 ) INS-82009_FOV_CLASS_SPEC = 'ANGLES' INS-82009_FOV_REF_VECTOR = ( +1.0000000000000000 0.0000000000000000 0.0000000000000000 ) INS-82009_FOV_REF_ANGLE = ( 90.0 ) INS-82009_FOV_ANGLE_UNITS = 'DEGREES' \begintext SRU Pixel Parameters: ---------------------------------------------------------- These parameters describe the pixel structure associated with the instruments and their fields of views. In some cases this is a generalization of the notion of pixel, in that instead of representing pixels on a CCD they may represent a collection of individual detectors. Stellar Reference Unit-A (SRU-A): \begindata INS-82001_FOV_CENTER_PIXEL = ( 511.5, 511.5 ) INS-82001_PIXEL_SAMPLES = ( 1024 ) INS-82001_PIXEL_LINES = ( 1024 ) \begintext Stellar Reference Unit-B (SRU-B): \begindata INS-82002_FOV_CENTER_PIXEL = ( 511.5, 511.5 ) INS-82002_PIXEL_SAMPLES = ( 1024 ) INS-82002_PIXEL_LINES = ( 1024 ) \begintext SRU-A Radiator (SRU-A_RAD): \begindata INS-82008_FOV_CENTER_PIXEL = ( 0, 0 ) INS-82008_PIXEL_SAMPLES = ( 1 ) INS-82008_PIXEL_LINES = ( 1 ) \begintext SRU-B Radiator (SRU-B_RAD): \begindata INS-82009_FOV_CENTER_PIXEL = ( 0, 0 ) INS-82009_PIXEL_SAMPLES = ( 1 ) INS-82009_PIXEL_LINES = ( 1 ) \begintext NAIF ID Code to Name Mapping ---------------------------------------------------------- The following keywords define names for the corresponding ID Codes. See [4] for details. \begindata NAIF_BODY_NAME += ( 'CASSINI_SRU-A' ) NAIF_BODY_CODE += ( -82001 ) NAIF_BODY_NAME += ( 'CASSINI_SRU-B' ) NAIF_BODY_CODE += ( -82002 ) NAIF_BODY_NAME += ( 'CASSINI_SRU-A_RAD' ) NAIF_BODY_CODE += ( -82008 ) NAIF_BODY_NAME += ( 'CASSINI_SRU-B_RAD' ) NAIF_BODY_CODE += ( -82009 ) \begintext Platform ID ---------------------------------------------------------- The SRU instrument is mounted on the Remote Sensing Palette, which is connected to the Cassini Spacecraft body. Therefore the value in the keywords below are -82000. \begindata INS-82001_PLATFORM_ID = ( -82000 ) INS-82002_PLATFORM_ID = ( -82000 ) INS-82008_PLATFORM_ID = ( -82000 ) INS-82009_PLATFORM_ID = ( -82000 ) \begintext