KPL/IK HUYGENS DISR Instrument Kernel =============================================================================== This Huygens SPICE instrument kernel (I-kernel) contains the instrument geometric parameters for the Descent Imager/Spectral Radiometer. Version and Date ------------------------------------------------------------------------------- Version 0.2 -- October 8, 2019 -- Alfredo Escalante, ESAC/ESA Marc Costa Sitja, ESAC/ESA Instruments defined with respect to the reference frame of each imager. Version 0.1 -- July 9, 2019 -- Marc Costa Sitja, ESAC/ESA Format corrections for first release. Version 0.0 -- August 1, 2018 -- Alfredo Escalante, ESAC/ESA Initial draft. References ------------------------------------------------------------------------------- 1. ``Frames Required Reading'' 2. ``Kernel Pool Required Reading'' 3. ``C-kernel Required Reading'' 2. ``Data Archive Users Guide for the Descent Imager and Spectral Radiometer (DISR) on the Huygens Probe'', Contact Information ------------------------------------------------------------------------------- If you have any questions regarding this file contact the ESA SPICE Service (ESS) at ESAC: Marc Costa Sitja (+34) 91-8131-457 esa_spice@sciops.esa.int, marc.costa@esa.int Alfredo Escalante Lopez alfredoescalante95@gmail.com 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 HUYGENS instrument ID code, constructed using the spacecraft ID number (-150) followed by the three digit ID number for SLI (101), the MRI (102) or the HRI (103). The remainder of the keyword is an underscore character followed by the unique name of the data item. For example, the boresight of the Side Looking Imager is specified by INS-150101_BORESIGHT 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 same keyword appears more than once within a single file, the last assignment supersedes any earlier assignments. Instrument Overview ------------------------------------------------------------------------------- From [2]: The DISR camera consists of three imagers oriented vertically. All three take pictures in the probes +Z direction (in azimuth), cf. With the Side Looking Imager (SLI) viewing from 6 deg above the horizon to nearly 45 deg below the horizon (by 25.6 deg wide), the Medium Resolution Imager (MRI or DLI2) picks up at 44 degrees below the horizon (1 degree overlap), and extends down to ~16 degrees from Nadir (21.1 degrees wide). The High Resolution Imager (HRI or DLI1) overlaps significantly with the MRI, covering angles from 6.4 degrees to 21.6 degrees above Nadir but is only 9.6 degrees wide. The three imagers are exposed simultaneously yielding a combined image that covers from 6 degrees above the horizon to about 6 degrees above nadir, and is mostly about 25 degrees wide. Mounting Alignment ------------------------------------------------------------------------------- Refer to the latest version of the Cassini Huygens Probe Frames Definition Kernel (FK) [4] for the DISR reference frame definitions and mounting alignment information. FOV Definition --------------------------------------------------------------------------- \begindata INS-150101_NAME = 'HUYGENS_DISR_SLI' INS-150101_BORESIGHT = ( 0.0 0.0 +1.0 ) INS-150101_FOV_FRAME = 'HUYGENS_DISR_SLI' INS-150101_FOV_SHAPE = 'RECTANGLE' INS-150101_FOV_CLASS_SPEC = 'ANGLES' INS-150101_FOV_REF_VECTOR = ( 0.0 +1.0 0.0 ) INS-150101_FOV_REF_ANGLE = ( 12.8 ) INS-150101_FOV_CROSS_ANGLE = ( 25.5 ) INS-150101_FOV_ANGLE_UNITS = 'DEGREES' INS-150102_FOV_FRAME = 'HUYGENS_DISR_MRI' INS-150102_FOV_SHAPE = 'RECTANGLE' INS-150102_BORESIGHT = ( 0.0 0.0 +1.0 ) INS-150102_FOV_CLASS_SPEC = 'ANGLES' INS-150102_FOV_REF_VECTOR = ( 0.0 +1.0 0.0 ) INS-150102_FOV_REF_ANGLE = ( 10.55 ) INS-150102_FOV_CROSS_ANGLE = ( 15 ) INS-150102_FOV_ANGLE_UNITS = 'DEGREES' INS-150103_FOV_FRAME = 'HUYGENS_DISR_HRI' INS-150103_FOV_SHAPE = 'RECTANGLE' INS-150103_BORESIGHT = ( 0.0 0.0 +1.0 ) INS-150103_FOV_CLASS_SPEC = 'ANGLES' INS-150103_FOV_REF_VECTOR = ( 0.0 +1.0 0.0 ) INS-150103_FOV_REF_ANGLE = ( 4.8 ) INS-150103_FOV_CROSS_ANGLE = ( 7.6 ) INS-150103_FOV_ANGLE_UNITS = 'DEGREES' \begintext Optical Parameters --------------------------------------------------------------------------- Focal Length is in millimeters and angular sizes on radians. \begindata INS-121310_FOCAL_LENGTH = ( 6.262 ) INS-121310_FOV_ANGULAR_SIZE = ( 0.44680428, 0.89011791 ) INS-121310_IFOV = ( 0.0035 ) INS-121320_FOCAL_LENGTH = ( 10.841 ) INS-121320_FOV_ANGULAR_SIZE = ( 0.3682645, 0.52359877 ) INS-121320_IFOV = ( 0.0021 ) INS-121320_FOCAL_LENGTH = ( 21.463 ) INS-121320_FOV_ANGULAR_SIZE = ( 0.1675516, 0.26529005 ) INS-121320_IFOV = ( 0.001 ) \begintext Detector Parameters --------------------------------------------------------------------------- Pixel Size in millimeters. \begindata INS-150101_PIXEL_SAMPLES = ( 128 ) INS-150101_PIXEL_LINES = ( 254 ) INS-143041_PIXEL_SIZE = ( 0.023, 0.245 ) INS-150102_PIXEL_SAMPLES = ( 176 ) INS-150102_PIXEL_LINES = ( 254 ) INS-143041_PIXEL_SIZE = ( 0.023, 0.245 ) INS-150103_PIXEL_SAMPLES = ( 160 ) INS-150103_PIXEL_LINES = ( 254 ) INS-143041_PIXEL_SIZE = ( 0.023, 0.245 ) \begintext Platform ID --------------------------------------------------------------------------- This number is the NAIF instrument ID of the platform on which the camera is mounted. \begindata INS-150101_PLATFORM_ID = ( -150000 ) INS-150102_PLATFORM_ID = ( -150000 ) INS-150103_PLATFORM_ID = ( -150000 ) \begintext End of IK file.