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 0.2 -- May 11, 2016 -- Jorge Diaz del Rio, ODC Space Added naming conventions and conventions for specifying data section. Corrected typos in text. Preliminary version. Pending review by the JANUS instrument team. 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 0.7, 10 November 2015 Contact Information ------------------------------------------------------------------------------- If you have any questions regarding this file contact SPICE support at ESAC: Marc Costa Sitja (+34) 91-8131-457 mcosta@sciops.esa.int, esa_spice@sciops.esa.int or NAIF at JPL: Boris Semenov (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. 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 (-907) 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 -907200 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-907200_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 is the Three Mirror Anastigmat (TMA). The camera is composed by three mirrors sharing the same optical axis. The first mirror is concave off-axis hyperboloid, the secondary mirror is convex with spherical shape while the tertiary mirror is a concave off-axis oblate ellipsoid. The optical system has on-centered unobstructed virtual entrance pupil and off-centered field of view. The main specifications of the optical system are provided in the following table: Specification Value ----------------------- ------------- Effective Focal Length 467 mm F/# 4.68 Field of View 1.72 x 1.29 degrees Detector format 2000 (H) x 1500 (V) pixels Pixel size 7 micrometer Plate scale 15microrad/pixel Spectral range 350 - 1050 nm The detector is rectangular with format 2000x1500 pixels and pixel size of 7 micrometer. The short side of the detector is parallel to the flight direction (along track - XZ spacecraft plane) while the long side perpendicular to it in order to maximize the imaging coverage. In the JANUS Camera has a set of 13 optical filters with different bandwidth and central wavelength. The list of the filters is given 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 These 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 -907200. ^ +Yjanus ^ pixel 1 | | Direction .-----------------|-----------------. ------ | of | | | ^ | Flight | | | | | | | | | | | | +Xjanus | | | | 1500 pixels <------------------------X | | 1.29 degrees | | | | | | | | | | | v '-----------------------------------' ------ | | |<--------------------------------->| | 2000 pixels | +Zjanus is into the 1.72 degrees page Optical Parameters ------------------------------------------------------------------------------- TBD; need consultation with JANUS instrument team Detector Parameters ------------------------------------------------------------------------------- TBD; need consultation with JANUS instrument team 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. \begindata INS-907200_FOV_FRAME = 'JUICE_JANUS' INS-907200_FOV_SHAPE = 'RECTANGLE' INS-907200_BORESIGHT = ( 0.000000 0.000000 1.000000 ) INS-907200_FOV_CLASS_SPEC = 'ANGLES' INS-907200_FOV_REF_VECTOR = ( 1.000000 0.000000 0.000000 ) INS-907200_FOV_REF_ANGLE = ( 0.015000 ) INS-907200_FOV_CROSS_ANGLE = ( 0.011250 ) INS-907200_FOV_ANGLE_UNITS = 'RADIANS' \begintext