Data Set Overview
  =================
    There are multiple methods of performing radiometric correction, 
    distinguished by the RADIOMETRIC_CORRECTION_TYPE keyword. The most 
    common are TAMCAL, RACCAL, MIPLRAD, MIPLRAD2, and MIPLRAD3.

  
    1. TAMCAL Method (SSI Team)

    This refers to radiometric correction of SSI instrument data only,
    performed by the SSI instrument team (Texas A&M University and
    University of Arizona) using their suite of software tools. It is
    the most precise correction method applicable to SSI data.

    There are 2 general types of SSI Radiometrically-corrected RDR products
    that are generated by the SSI instrument team: Radiance-calibrated and
    Radiance-factor calibrated. Additional details on the radiometric
    processing and calibration of SSI images can be found in the SSI
    Calibration Report.
    
    1.1. Radiance-calibrated RDRs ('RAD', 'RAL')
    
    The non-linearized RDRs are generated from EDRs. They have all of the
    major instrumental/environmental calibrations applied, such as bias
    removal, dark current removal, electronic shutter smear effect removal,
    flat field correction, and bad pixel repair. Then they have been scaled
    to absolute radiance units using pre-flight radiometric calibration
    coefficients. The units on these files are (W/m^2/nm/sr).
    
    An analogous RDR file type exists for the linearized
    (geometrically-corrected) SSI RDR as well, and it is labeled with the
    'RAL' product type identifier to correspond with the 'RAD' type. In
    addition, floating point versions of this RDR may also be generated.
    
    1.2. Radiance factor-calibrated RDRs ('IOF', 'IOL')
    
    The non-linearized RDRs are generated from EDRs or 'RAD' RDRs. They have
    all the major instrumental/environmental calibrations applied and have
    been scaled to absolute radiance units as described above, and then have
    been divided by the absolute radiance of the Sun at the top of the
    Martian atmosphere within the appropriate SSI bandpass, to generate
    radiance factor, or 'I over F' values, where I is the radiance from the
    Martian scene and pi * F is the radiance from the Sun at the top of the
    Martian atmosphere (or on the surface, as determined by reflectance
    calibration targets. Since the solar radiance in the same units as the
    Mars scene radiance was divided out, these files are unitless but
    typically have values in the range of 0.0 to 1.0 (for example, average
    bright Mars soils exhibit I/F ~ 0.35 at 750 nm and I/F ~ 0.05 at 410
    nm).
    
    As with the 'RAD' RDR type, there exists a linearized version of the IOF
    type of Radiometricallycorrected RDR, called 'IOL'. A floating point
    version of this RDR may also be generated.
    
    2. RACCAL Method (RAC Team)
    
    This refers to radiometric correction of RAC instrument data only,
    performed by the RAC instrument team (MPS) using their suite of RACCAL
    software tools. It is the most precise correction method applicable to
    RAC data. Note that radiometric correction of MECA-OM instrument data
    will be performed using the same tools employed for the RACCAL method.
    
    The RAC/OM calibration steps performed by the RACSoft package are
    described below:
    
        1. The bad pixel removal state replaces a number of pixels marked
        bad because of dust grains on the CCD or hot electron production.
        The bad pixels are replaced by an interpolated value based on the
        surrounding pixels.
        
        2. The bias subtraction state subtracts the ADC digital offset
        from the image.
        
        3. The RAC and the OM uses an electronic shutter where the image
        data is fast clocked to a covered aread on the CCD at the end of
        the exposure. During the fast clocking each row experiences
        addition light from other parts of the scene. The electronic
        shutter correction subtracts from row N the summed DN signal of
        row 0 to N-1 scaled by the time it takes to clock a row one step
        on the CCD.
        
        4. The dark current correction subtracts an estimated mean value
        of dark current based on the temperature of the CCD. This simple
        scheme (as compared to the SSI) is used because the RAC and OM has
        a very low dark current production under Mars conditions.
        
        5. The flatfield correction divider the image by the relevant
        flatfield for the given focus motor step.
        
        6. The OM calibration is finished after the flat field correction
        since good absolute calibration data is not available for the OM.
        
        7. The final step of the RAC calibration is to divide the image by
        the absolute calibration constant for the given focus motor step.
        The calibration constant is given by the ground absolute calibration
        at focus motor step 306 (near infinite focus) and a correction
        factor derived for the change in instantaneous field of view between
        focus step 306 and the active focus step.  

    3. MIPLRAD, MIPLRAD2, MIPLRAD3 Methods
    These refer to radiometric correction of any camera instrument data 
    systematically performed by MIPL (OPGS at JPL) to meet tactical time 
    constraints imposed by Arm Planners. The resulting rad-corrected
    RDRs are integrated into terrain mesh products used for RA trench 
    digging. For SSI and RAC instrument data, these methods are less 
    precise than the TAMCAL and RACCAL methods previously discussed. The 
    MIPL radiometrically-corrected RDR filenames carry the product type 
    designators RAD (non-linearized) or RAL (linearized).

    MIPLRAD, MIPLRAD2, and MIPLRAD3 are first-order corrections only and 
    should be considered approximate. All three apply the following 
    corrections: dark current, temperature-compensated responsivity, 
    exposure time, binning correction, and flat field. The result is 
    calibrated to physical units for PHX of W/m^2/nm/sr. The actual 
    algorithm and equations used for the three MIPLRAD's are in the data 
    product SIS [ALEXANDERETAL2008]. In all cases, ALL_CAPITALS serve to 
    denote keyword names in the PDS label.

    The only difference between the three MIPLRAD methods is in the dark 
    current calculation that is used. MIPLRAD uses a dark current 
    calculation developed by Adam Shaw at the University of Arizona. 
    MIPLRAD2 (the default) uses a calculation developed by Mark Lemmon at 
    Texas A&M University. MIPLRAD3 uses the Lemmon calculation with a 
    simplification for efficiency (described in the data product SIS).

    Dark current applies only to SSI. RAC dark current is assumed to be 0 
    in all three methods.

    More information is found in ALEXANDERETAL2008, LEMMONETAL2007, and
    LEMMONETAL2008.
    
  Processing
  ==========
    Phoenix SSI RDRs are considered Level 3 (Calibrated Data equivalent 
    to NASA Level 1-A), Level 4 (Resampled Data equivalent to NASA Level 
    1-B), or Level 5 (Derived Data equivalent to NASA Level 1-C, 2 or 3). 
    The RDRs are to be reconstructed from Level 2 edited data, and are 
    to be assembled into complete images that may include radiometric 
    and/or geometric correction.

    Phoenix SSI instrument EDRs and RDRs will be generated by JPL's 
    Multimission Instrument Processing Laboratory (MIPL) as part of the 
    OPGS subsystem of the Phoenix GDS. RDRs will also be generated by 
    the SSI science instrument team at the SOC facility at the 
    University of Arizona, as well as at its home institution, Texas 
    A&M.

    RDR data products will be generated by, but not limited to, MIPL 
    using the Mars Suite of VICAR image processing software at JPL, and 
    the SSI science instrument team using TAMCAL and RACCAL software at 
    the SOC facility at the University of Arizona and at the team's home 
    institution at Texas A&M Univerisity. The RDRs produced will be 
    'processed' data. The input will be one or more Camera EDR or RDR 
    data products and the output will be formatted according to the data 
    product SIS [ALEXANDERETAL2008]. Additional meta-data may be added by
    the software to the PDS label.

  Data
  ====
    RDR products generated by MIPL will have a VICAR label wrapped by a
    PDS label, and their structure can include the optional EOL label
    after the binary data. RDR products not generated by MIPL may
    contain only a PDS label. Or, RDR products conforming to a standard
    other than PDS, such as JPEG compressed or certain Terrain products,
    are acceptable without a PDS header during mission operations, but
    may not be archivable.

    The RDR data product is comprised of radiometrically decalibrated
    and/or camera model corrected and/or geometrically altered versions
    of the raw camera data, in both single and multi-frame (mosaic)
    form. Most RDR data products will have PDS labels, or if generated
    by MIPL (OPGS), dual PDS/VICAR labels. Non-labeled RDRs include JPEG
    compressed products and the Terrain products.

  Software
  ========
    The TAMCAL and RACCAL software was used to generate these RDRs.


  Media/Format
  ============
    The data set will initially be delivered and kept online.  Upon
    Mission completion, the SSI Operations RDRs will be delivered to PDS 
    on DVD.

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