KPL/IK ALICE Instrument kernel =========================================================================== This instrument kernel (I-kernel) contains Rosetta ALICE optics, detector, and field-of-view parameters. Version and Date --------------------------------------------------------------------------- Version 1.0 -- March 15, 2005 -- Boris Semenov, NAIF/JPL Version number change for the first official release. Version 0.2 -- March 15, 2005 -- Boris Semenov, NAIF/JPL Corrected FOV definition and relevant parameters and descriptions to ``line up'' the slit with +X axis of the ALICE frame. Version 0.1 -- September 2, 2004 -- Boris Semenov, NAIF/JPL Filled in instrument overview section (copied from [6]). Version 0.0 -- August 3, 2004 -- Boris Semenov, NAIF/JPL VERY PRELIMINARY VERSION. References --------------------------------------------------------------------------- 1. ``Kernel Pool Required Reading'' 2. ``C-kernel Required Reading'' 3. ``ALICE EID, Part B'', ROS-EST-RS-3005/EID B, 2001-02-15 4. Rosetta Frames Definition Kernel (FK), latest version. 5. ``ALICE: Experiment User Manual'', 8225-EUM-01, 2002-12-XX 6. ESA Science and Technology Web Server, Rosetta Instruments Area, http://sci.esa.int/science-e/www/object/index.cfm?fobjectid=35061 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 Rosetta instrument ID code, constructed using the spacecraft ID number (-226) followed by the NAIF three digit ID number for ALICE (120). ALICE ID(s) is defined in [4]. 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 ALICE optics is specified by INS-226120_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 [6]: ALICE, an Ultraviolet Imaging Spectrometer, will characterize the composition of the nucleus and coma, and the nucleus/coma coupling of comet 67 P/Churyumov-Gerasimenko. This will be accomplished through the observation of spectral features in the extreme and far ultraviolet ( EUV/FUV) spectral regions from 70 to 205 nm. ALICE will make measurements of noble gas abundances in the coma, the atomic budget in the coma, and major ion abundances in the tail and in the region where solar wind particles interact with the ionosphere of the comet. ALICE will determine the production rates, variability, and structure of H2O and CO, and CO2 gas surrounding the nucleus and the far-UV properties of solid grains in the coma. ALICE will also map the cometary nucleus in the FUV, and study Mars and the Rosetta asteroid flyby targets while en route to Churyumov-Gerasimenko. Summary of ALICE Characteristics Wavelength range (nm): 70-205 Spectral resolution, (extended source, FWHM) (nm): 1.0 (at 70 nm), 1.3 (at 205 nm) Spectral resolution, (point source, FWHM) (nm): 0.3-0.5 Spatial resolution (degrees): 0.1 × 0.5 Nominal sensitivity (counts s-1 R-1): 0.5 (at 190 nm); 7.8 (at 115 nm) Field of view (degrees): 0.1 x 6.0 Pointing: Boresight with OSIRIS, VIRTIS Observation types: Nucleus imaging and spectroscopy; Coma spectroscopy; Jet and grain spectrophotometry; Stellar occultations (secondary observations) Telescope: 40 × 40 mm entrance pupil; 41 × 65 mm, f3, off-axis paraboloid primary mirror; 120 mm focal length Spectrograph: Rowland Circle style imaging spectrograph; 0.1 x 6 deg entrance slit; 50 x 50 mm toroidal holographic diffraction grating Detector: 2-D (1024 × 32 pixels) microchannel plate Mass (kg): 2.7 Dimensions (l x w x h, mm): 204 x 413 x 140 Power consumption (average, W): 5.6 Mounting Alignment -------------------------------------------------------- Refer to the latest version of the Rosetta Frames Definition Kernel (FK) [4] for the ALICE reference frame definitions and mounting alignment information. Apparent FOV Layout -------------------------------------------------------- WARNING --- the description/diagram below have not been verified WARNING --- the description/diagram below do not show the slit configuration, with the three slit parts and the pinhole. This section provides a diagram illustrating the ALICE apparent detector layout in the corresponding reference frame. ^ | direction of | flight | ^ +Xalice (along track) | --- +-|-+ Line 1 ^ | | | | | | | | | | | | | | | | 6 degrees 12 lines | x-------------> +Yalice (cross track) | | | | | | | | | v | | --- +---+ Line 12 1 pixel | | 0.1 degrees ->|---|<--------- | | Boresight (+Z axis) is into the page Although there are 24 physical pixels in along-track, spatial direction, they are used in pairs. So the total number of "spatial" resolution pixels in the column could be considered to be 12. As the light entering the instrument passes through a narrow slit parallel to the +X axis (along-track direction), the apparent size FOV in cross-track direction is equivalent to just one pixel (as shown on the diagram.) The physical 1024 pixels that the detector has in the cross-track direction are used to achieve desired spectral resolution. Optical Parameters -------------------------------------------------------- The following ALICE nominal first order optical parameters are included in the data section below, from [3]: ----------------------------------------------------------------- parameter value note ----------------------------------------------------------------- Focal Length, mm 120.0 f/ratio f/3 IFOV, rad/pixel Cross-track 0.001745 Along-track 0.008727 Field of view (deg) Cross-track 0.1 Along-track 6.0 ----------------------------------------------------------------- FOV and IFOV parameters above are for the spatial direction. 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-226120_FOCAL_LENGTH = ( 120.0 ) INS-226120_F/RATIO = ( 3.0 ) INS-226120_FOV_ANGULAR_SIZE = ( 0.001745, 0.104720 ) INS-226120_IFOV = ( 0.001745, 0.008727 ) \begintext Detector Parameters -------------------------------------------------------- The nominal ALICE detector parameters from [6] are: ----------------------------------------------------------------- parameter value note ----------------------------------------------------------------- Detector Array Size ---- Physical Cross-track 1024 spectral dimension Along-track 36 center 24 are used is pairs Detector Array Size ---- Spatial Cross-track 1 Along-track 12 each is 2 physical pixels Detector Array Center -- Spatial Cross-track 0.5 Along-track 5.5 Pixel Size, microns ---- Spatial Cross-track 209.4 computed from IFOV and FL Along-track 1047.0 computed from IFOV and FL ----------------------------------------------------------------- The values are given in microns for PIXEL_SIZE keywords and in counts for PIXEL_SAMPLES, PIXEL_LINES, and CENTER keywords. \begindata INS-226120_PIXEL_SIZE = ( 209.4, 1047.0 ) INS-226120_PIXEL_SAMPLES = ( 1 ) INS-226120_PIXEL_LINES = ( 12 ) INS-226120_CCD_CENTER = ( 0.5, 5.5 ) \begintext FOV Definitions --------------------------------------------------------------------------- This section contains definitions for the ALICE FOV. This definition is provided in the format required by the SPICE (CSPICE) function GETFOV (getfov_c). The set of assignments in the data section below defines the ALICE FOV with respect to the ROS_ALICE frame to be a rectangle with the corners defined by the first and last pixels of the spatial, along-track column and the boresight along the +Z axis of the ROS_ALICE frame. This FOV definition uses angular extent style specification with the cross and along track angular sizes taken from the ``Optics Parameters'' section above. \begindata INS-226120_FOV_FRAME = 'ROS_ALICE' INS-226120_FOV_SHAPE = 'RECTANGLE' INS-226120_BORESIGHT = ( 0.000000 0.000000 120.000000 ) INS-226120_FOV_CLASS_SPEC = 'ANGLES' INS-226120_FOV_REF_VECTOR = ( 0.000000 1.000000 0.000000 ) INS-226120_FOV_REF_ANGLE = ( 0.05 ) INS-226120_FOV_CROSS_ANGLE = ( 3.00 ) INS-226120_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. For ALICE it is the spacecraft. \begindata INS-226120_PLATFORM_ID = ( -226000 ) \begintext