KPL/IK JANUS Instrument Kernel =============================================================================== This instrument kernel (I-kernel) contains the JUICE Jovis, Amorum ac Natorum Undique Scrutator (JANUS) camera system optics, detector and field-of-view (FOV) paramters. Version and Date ------------------------------------------------------------------------------ Version 0.7 -- June 30, 2022 -- Marc Costa Sitja, ESAC/ESA Corrected INS-28200_CCD_CENTER definition and fixed descriptions. Version 0.6 -- January 08, 2021 -- Alfredo Escalante Lopez, ESAC/ESA, Pasquale Palumbo, Parthenope, Cecilia Tubiana, IAPS/INAF Updated Instrument Description, Optical Parameters, and Detector Parameters sections. Corrected typos. Corrected INS-28200_PIXEL_SAMPLES and INS-28200_PIXEL_LINES in Detector Parameters section. Added some optical parameters. Version 0.5 -- August 01, 2016 -- Marc Costa Sitja, ESAC/ESA, Thomas Roatsch, DLR Added Camera sensor definitions as indicated by Thomas Roatsch and corrected the required values. Version 0.4 -- July 11, 2016 -- Marc Costa Sitja, ESAC/ESA Corrected instrument description. Corrected FOV value now provided in degrees instead of radians. Initial Release. Pending review by the JANUS instrument team. Version 0.3 -- June 04, 2016 -- Marc Costa Sitja, ESAC/ESA Updated all NAIF ID codes from -907* to -28* since the JUICE spacecraft NAIF ID has been updated from -907 to -28. Version 0.2 -- May 11, 2016 -- Jorge Diaz del Rio, ODC Space Added naming conventions and conventions for specifying data section. Corrected typos in text. Version 0.1 -- March 04, 2016 -- Jorge Diaz del Rio, ODC Space Preliminary version. Pending review by the JANUS instrument and JUICE Science Operations Working Group team. Version 0.0 -- July 24, 2013 -- Marc Costa Sitja, ISDEFE/ESA Initial Release. References ------------------------------------------------------------------------------ 1. ``Kernel Pool Required Reading'' 2. ``C-kernel Required Reading'' 3. JUICE Frames Definition Kernel (FK), latest version. 4. ``JUICE - Jupiter Icy Moons Explorer. Exploring the emergence of habitable worlds around gas giants. Definition Study report,'' ESA/SRE(2014)1, September 2014 (JUICE Red book v1.0) 5. ``JANUS - Camera for the ESA JUICE mission Experiment Interface Document - Part B,'' JUI-JAC-JAN-EID-B-001, Issue E, 30 January 2020 (formally delivered in July 2020) 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 the JUICE Science Operations Center at ESAC: Marc Costa Sitja (+34) 91-8131-236 Marc.Costa@ext.esa.int Implementation Notes ------------------------------------------------------------------------------ Applications that need SPICE I-kernel data must ``load'' the I-kernel file, normally during program initialization. The SPICE routine FURNSH loads a kernel file into the pool as shown below. CALL FURNSH ( 'frame_kernel_name' ) -- FORTRAN furnsh_c ( "frame_kernel_name" ); -- C cspice_furnsh, frame_kernel_name -- IDL cspice_furnsh( 'frame_kernel_name' ) -- MATLAB 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''. Once the file has been loaded, the SPICE routine GETFOV (getfov_c in C, cspice_getfov in IDL and MATLAB) can be used to retrieve FOV parameters for a given instrument or structure. The application program may obtain the value(s) for any other IK data item using the SPICELIB routines GDPOOL, GIPOOL, GCPOOL (gdpool_c, gipool_c, gcpool_c in C, cspice_gdpool, cspice_gipool, cspice_gcpool in IDL and MATLAB). See [1] for details. This file was created with, and can be updated with a text editor or word processor. Naming Conventions and Conventions for Specifying Data ------------------------------------------------------------------------------ All names referencing values in this IK file start with the characters `INS' followed by the NAIF JUICE spacecraft ID number (-28) followed by a NAIF three digit ID code for one of the JANUS camera. This is the full list of names and IDs for the JANUS sensors described by this IK file: Name NAIF ID --------------------- --------- JUICE_JANUS -28200 The remainder of the keyword name is an underscore character followed by the unique name of the data item. For example, the JANUS Camera boresight direction in the JUICE_JANUS frame is specified by: INS-28200_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. Instrument Description and Overview ------------------------------------------------------------------------------ This section is extracted from the Experiment Interface Document - Part B (see [5]) Instrument Description: ----------------------- The optical solution adopted as JANUS camera baseline looks like a Ritchey Chretien (RC) configuration with a dioptric corrector working in convergent beam. The elements that constitute the telescope are the primary mirror made of Fused Silica with hyperbolic surface with 10th order coefficient, the secondary mirror made of Zerodur with hyperbolic surface with 10th order coefficient, the dioptric corrector composed by three spherical elements made of Fused Silica, the filters wheel with 13 different filters made of Fused Silica with large, medium and narrow waveband, the detector window made of Fused Silica. The basic idea driving the architecture for the JANUS telescope is to design an anastigmatic catadioptric telescope, athermalized and structurally stable, that can be mounted and aligned to mechanical tolerance and where the only adjustable element is the secondary mirror. In order to achieve this, the magnification ratio between the focal length of the telescope with respect to the focal length of the primary mirror has been reduced. Due to the wide spectral range, the power of the dioptric element have to be close to zero in order to design an apochromatic system. The main specifications of the optical system are provided in the following table: Specification Value -------------------------------- -------------------------------- Effective Focal Length 467 mm F/# w/o obstruction 4.02 F/# w/ obstruction (radiometric) 4.5 Field of View 1.72 x 1.29 degrees Detector format 2000 (H) x 1504 (V) pixels Pixel size 7 micrometer Plate scale 15 microrad/pixel = 3.09"/pixel Spectral range 340 - 1080 nm The detector is rectangular with format 2000x1504 pixels and pixel size of 7 micrometer. The short side of the detector +Y JUICE_JANUS is parallel to +Y JUICE_SPACECRAFT (flight direction), while the long side +X JUICE_JANUS is parallel to +X JUICE_SPACECRAFT (across track) in order to maximize the imaging coverage while in Ganymede in orbit and during satellites closest approach. The JANUS Camera is equipped with a set of 13 optical filters (1 Panchromatic, 4 Broad-Band, and 8 Narrowband) covering the wavelength range from 340 to 1080 nm. The filters are mounted on the Filter Wheel Mechanism (FWM), which positions the optical filters in front of the image detector with the necessary accuracy. Mounting Alignment ------------------------------------------------------------------------------ Refer to the latest version of the JUICE Frames Definition Kernel (FK) [3] for the JANUS reference frame definitions and mounting alignment information. JANUS Apparent Field-of-View Layout ------------------------------------------------------------------------------ This diagram illustrates the JANUS apparent FOV layout in the corresponding reference frame when operating in normal mode (no-binning). This FOV is associated with detector instrument IDs -28200. ^ +Yjanus ^ pixel 1 | | Direction .-----------------|-----------------. ------ | of | | | ^ | Flight | | | | | | | | | | | | +Xjanus | | | | 1504 pixels <------------------------X | | 1.29 degrees | | | | | | | | | | | v '-----------------------------------' ------ | | |<--------------------------------->| | 2000 pixels | +Zjanus is into the 1.72 degrees page Optical Parameters ------------------------------------------------------------------------------ The JANUS camera is equipped with 13 filters with different bandwidth and central wavelength. The list of the filters is provided in the following table: Center/ Filter ID Bandpass[nm] Notes ---------- ------------ --------------------------------------------- FPAN 650/500 Panchromatic (clear) - monochromatic imaging FBLUE 450/60 Blue - satellite colours FGREEN 530/60 Green, background for Na - satellite colors FRED 656/60 Red, background for Halph - satellite colors CMT medium 750/20 Continuum for strong Jovian Methane band, geology Na 590/10 Sodium D-lines in exospheres MT strong 889/20 Strong Jovian Methane band CMT strong 940/20 Continuum for medium Jovian Methane band, Fe2+ on satellites MT medium 727/10 Medium Jovian Methane band Violet 410/80 UV slope NIR 1 910/80 Fe2+, Io lava spots NIR 2 1000/150 Fe2+, Io lava spots - GALA laser altimeter footprint Halpha 656/10 Halpha-line for aurorae and lightning Detector Parameters ------------------------------------------------------------------------------ The JANUS camera uses a rectangular CMOS detector, with the following parameters: Parameter Value ---------------- -------------------------------- Detector size SAMPLES 1504 px LINES 2000 px Detector center (752.5, 1000.5) Pixel size 7 micrometer IFOV 15 microrad The values are given in microns for PIXEL_SIZE keywords, radians in IFOV and in counts for PIXEL_SAMPLES, PIXEL_LINES, and CCD_CENTER keywords. \begindata INS-28200_PIXEL_SAMPLES = ( 1504 ) INS-28200_PIXEL_LINES = ( 2000 ) INS-28200_PIXEL_SIZE = ( 7 ) INS-28200_CCD_CENTER = ( 752.5, 1000.5 ) INS-28200_IFOV = ( 0.000015 ) \begintext JANUS Field of View Definition ------------------------------------------------------------------------------ The set of assignments in the data section below defines the JANUS FOVs with respect to the corresponding frame to be rectangles with the corners defined by CCD 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. This FOV definition corresponds to the NAIF Body Name: JUICE_JANUS. Please note that the FOV reference and cross angles are defined with half angle values. \begindata INS-28200_FOV_FRAME = 'JUICE_JANUS' INS-28200_FOV_SHAPE = 'RECTANGLE' INS-28200_BORESIGHT = ( 0.000000 0.000000 1.000000 ) INS-28200_FOV_CLASS_SPEC = 'ANGLES' INS-28200_FOV_REF_VECTOR = ( 0.000000 1.000000 0.000000 ) INS-28200_FOV_REF_ANGLE = ( 0.645000 ) INS-28200_FOV_CROSS_ANGLE = ( 0.860000 ) INS-28200_FOV_ANGLE_UNITS = 'DEGREES' \begintext End of IK file.