Online Reference: http://www-pdsimage.wr.usgs.gov/PDS/public/mapmaker/mapmkr.htm

 
 
        INSTRUMENT: VISUAL IMAGING SUBSYSTEM - CAMERA B
        SPACECRAFT: VIKING ORBITER 1
 
    Instrument Information
    ======================
      Instrument Id                  : VISB
      Instrument Host Id             : VO1
      Pi Pds User Id                 : MCARR
      Instrument Name                : VISUAL IMAGING SUBSYSTEM -
                                       CAMERA B
      Instrument Type                : VIDICON CAMERA
      Build Date                     : 1974-05-01
      Instrument Mass                : 22.700000
      Instrument Length              : 0.937000
      Instrument Width               : 0.218000
      Instrument Height              : 0.218000
      Instrument Serial Number       : SN04
      Instrument Manufacturer Name   : JET PROPULSION LABORATORY
 
 
    Instrument Description
    ======================
      Each Viking Orbiter was equipped with two identical vidicon
      cameras.  The camera system is commonly called the Visual
      Imaging Subsystem (VIS).  Each camera consists of a telescope,
      a slow scan vidicon, a filter wheel, and associated
      electronics.  The filter wheel contains blue, minus blue,
      violet, clear, green, and red filters.  The angular field of
      view as defined by the reseau pattern is 1.51 by 1.69 degrees.
      Since the scan lines go beyond the reseau pattern in the line
      direction the active field of view is about 1.54 degrees in
      this direction.  The actual ground area covered by an image
      varies as a function of spacecraft altitude and emission angle.
      The digital image is generated by scanning the vidicon face
      plate.  The signal is digitized as a 7-bit number.  The image
      contains 1056 horizontal lines.  There are 1182 samples in each
      line exposed to incoming light.  The vidicon samples 11 pixels
      on either side of the raster onto an opaque mask located at the
      front of each vidicon.  Hence, 1204 samples per line are
      telemetered to Earth, but only 1182 contain information.  Each
      camera can be commanded to acquire an image every 8.96 seconds.
      By alternating cameras, an image can be taken every 4.48
      seconds.
 
 
    Science Objectives
    ==================
      The first objective of the imaging system was to characterize
      potential landing sites in support of site selection.
      Additional objectives of the imaging system were to study the
      photometric and colorimetric properties of the surface
      discovered by Mariner 9 in order to better understand the
      geological history of Mars atmosphere.
 
 
    Operational Considerations
    ==========================
      Each Viking Orbiter camera contained a filter wheel with five
      filters and a clear position, i.e., no filter.  An image could
      be acquired using one of the six filters types, which included
      blue, minus blue, violet, clear, green, and red.  The filter
      wheel could be stepped only one position between each exposure.
      Three mode parameters or camera states could be set for a given
      exposure.  There was the light flood condition flag.  Light
      flooding was used to reduce the residual image from the
      previous exposure.  Eight small incandescent bulbs exposed the
      vidicon beyond saturation.  There were also two gain states:
      low and high.  The high gain state increased the gain by a
      factor of 2.  There was also an exposure offset that would
      provide a positive signal (DN) from the camera even for a zero
      exposure.
 
 
    Calibration Description
    =======================
      The radiometric calibration converts the digitized signal
      received from the camera (DN value) into a quantity that is
      proportional to the radiance reaching the sensor.  The
      sensitivity of the vidicon varies across the field of view.
      The sensitivity of the vidicon also varies with time.  Each
      Viking Orbiter imaging instrument was calibrated before flight.
      In addition, changes in the calibration over time have been
      estimated from analyses of images of deep space and dust
      storms.  The radiometric calibration applies additive and
      multiplicative corrections that account for the varying
      sensitivity of the vidicon.  The resulting values are
      proportional to radiance factor, which is defined as the ratio
      of the observed radiance to the radiance of a normally
      illuminated lambertian reflector of unit reflectance at the
      same heliocentric distance.  The geometric calibration removes
      electronic distortions and transforms the point perspective
      geometry of the original image into a map projection.  The
      electronic distortions are barrel- shaped distortions from the
      electron beam readout and complex distortions from interactions
      between the charge on the vidicon face plate and the electron
      beam.  The electronic distortions are modeled by comparing the
      undistorted locations of reseau marks with the actual locations
      in an image.
 
 
    Section 'VISB'
    ==============
      Total Fovs                     : 1
      Data Rate                      : 2112000.000000
      Sample Bits                    : 7
 
 
      'VISB' Detectors
      ----------------
        VISB
 
 
      'VISB' Electronics
      ------------------
        VISB
 
 
      'VISB' Filters
      --------------
        BLUE
        CLEAR
        GREEN
        MINUS BLUE
        RED
        VIOLET
 
 
      'VISB' Section Optic IDs
      ------------------------
        VISB
 
 
      In modes
      --------
        ...
        ..D
        .G.
        .GD
        L..
        L.D
        LG.
        LGD
 
 
      'VISB' Section FOV Shape 'RECTANGULAR'
      --------------------------------------
        Section Id                     : VISB
        Fovs                           : 1
        Horizontal Pixel Fov           : 0.001420
        Vertical Pixel Fov             : 0.001420
        Horizontal Fov                 : 1.692000
        Vertical Fov                   : 1.533000
 
 
      'VISB' Section Parameter 'RADIANCE'
      -----------------------------------
        Radiance is the amount of energy per time per projected area
        per steradian.
 
        Instrument Parameter Name      : RADIANCE
        Sampling Parameter Name        : PIXEL
        Instrument Parameter Unit      : WATT/(METER*METER)/STERADIAN
        Sampling Parameter Resolution  : 0.001420
        Sampling Parameter Unit        : DEGREE
 
 
    Instrument Detector 'VISB'
    ==========================
      Detector Type                  : VIDICON
      Detector Aspect Ratio          : 1.120000
      Minimum Wavelength             : 0.350000
      Maximum Wavelength             : 0.650000
      Nominal Operating Temperature  : 288.000000
 
 
      Description
      -----------
        The VIS detector is a Westinghouse 5166 selenium vidicon.  It
        is about 3.7 cm (1-1/2 in.) in diameter.
 
 
      Sensitivity
      -----------
        The saturation current from the vidicon is 46 nA.  The
        residual dark current is 0.4 nA.  The response of the visual
        imaging subsystem is linear to first order.  Analyses of
        imaging data acquired inflight indicate that the system is
        linear to within 3% over its dynamic range.
 
 
    Instrument Electronics 'VISB'
    =============================
 
      Description
      -----------
        About 1000 electronic parts (e.g., vidicon filament voltage
        and alignment current regulators) were included per camera,
        divided between the camera head and an auxiliary chassis.
        (see Wellman et al, 1976)
 
 
    Instrument Filter '1 - BLUE'
    ============================
      Filter Name                    : BLUE
      Filter Type                    : INTERFERENCE
      Minimum Wavelength             : 0.350000
      Maximum Wavelength             : 0.530000
      Center Filter Wavelength       : 0.470000
 
 
      Description
      -----------
        The filter transmittance was measured using a Cary 14
        spectrophotometer with a spare set of filters.  (see Benesh
        and Thorpe, 1976)
 
 
    Instrument Filter '2 - MINUS BLUE'
    ==================================
      Filter Name                    : MINUS BLUE
      Filter Type                    : ABSORPTION
      Minimum Wavelength             : 0.480000
      Maximum Wavelength             : 0.700000
      Center Filter Wavelength       : 0.550000
 
 
      Description
      -----------
        The filter transmittance was measured using a Cary 14
        spectrophotometer with a spare set of filters.  (see Benesh
        and Thorpe, 1976)
 
 
    Instrument Filter '3 - VIOLET'
    ==============================
      Filter Name                    : VIOLET
      Filter Type                    : INTERFERENCE
      Minimum Wavelength             : 0.350000
      Maximum Wavelength             : 0.470000
      Center Filter Wavelength       : 0.440000
 
 
      Description
      -----------
        The filter transmittance was measured using a Cary 14
        spectrophotometer with a spare set of filters.  (see Benesh
        and Thorpe, 1976)
 
 
    Instrument Filter '4 - CLEAR'
    =============================
      Filter Name                    : CLEAR
      Minimum Wavelength             : 0.350000
      Maximum Wavelength             : 0.700000
      Center Filter Wavelength       : 0.520000
 
 
      Description
      -----------
        The filter transmittance was measured using a Cary 14
        spectrophotometer with a spare set of filters.  (see Benesh
        and Thorpe, 1976)
 
 
    Instrument Filter '5 - GREEN'
    =============================
      Filter Name                    : GREEN
      Filter Type                    : INTERFERENCE
      Minimum Wavelength             : 0.500000
      Maximum Wavelength             : 0.600000
      Center Filter Wavelength       : 0.530000
 
 
      Description
      -----------
        The filter transmittance was measured using a Cary 14
        spectrophotometer with a spare set of filters.  (see Benesh
        and Thorpe, 1976)
 
 
    Instrument Filter '6 - RED'
    ===========================
      Filter Name                    : RED
      Filter Type                    : ABSORPTION
      Minimum Wavelength             : 0.550000
      Maximum Wavelength             : 0.700000
      Center Filter Wavelength       : 0.590000
 
 
      Description
      -----------
        The filter transmittance was measured using a Cary 14
        spectrophotometer with a spare set of filters.  (see Benesh
        and Thorpe, 1976)
 
 
    Instrument Optics 'VISB'
    ========================
      Telescope Diameter             : 0.137000
      Telescope F Number             : 3.500000
      Telescope Focal Length         : 0.474448
      Telescope Resolution           : 0.000050
      Telescope Serial Number        : SN08
      Telescope T Number             : 5.340000
      Telescope T Number Error       : 0.020000
      Telescope Transmittance        : 0.430000
 
 
      Description
      -----------
        The telescope was an all spherical Schmidt- Cassegrain design
        employing a Mangin primary mirror.  Optical performance was
        70% response at 42 line pairs per millimeter.  (see Wellman
        et al, 1976)
 
 
        NOTE: The TELESCOPE_RESOLUTION given above is a line pair
        resolution, i.e., the geometrical size of a pixel times two.
 
 
    Instrument Mode '...'
    =====================
      Gain Mode Id                   : LOW
      Instrument Power Consumption   : 22.000000
 
 
      In sections
      -----------
        VISB
 
 
      Description
      -----------
        (see Wellman et al, 1976)
 
 
    Instrument Mode '..D'
    =====================
      Gain Mode Id                   : LOW
      Instrument Power Consumption   : 22.000000
 
 
      In sections
      -----------
        VISB
 
 
      Description
      -----------
        Light flood is off, gain is low, and exposure offset is on.
 
 
    Instrument Mode '.G.'
    =====================
      Gain Mode Id                   : HIGH
      Instrument Power Consumption   : 22.000000
 
 
      In sections
      -----------
        VISB
 
 
      Description
      -----------
        Light flood is off, gain is high, and exposure offset is off.
 
 
    Instrument Mode '.GD'
    =====================
      Gain Mode Id                   : HIGH
      Instrument Power Consumption   : 22.000000
 
 
      In sections
      -----------
        VISB
 
 
      Description
      -----------
        Light flood is off, gain is high, and exposure offset is on.
 
 
    Instrument Mode 'L..'
    =====================
      Gain Mode Id                   : LOW
      Instrument Power Consumption   : 22.000000
 
 
      In sections
      -----------
        VISB
 
 
      Description
      -----------
        Light flood is on, gain is low, and exposure offset is off.
 
 
    Instrument Mode 'L.D'
    =====================
      Gain Mode Id                   : LOW
      Instrument Power Consumption   : 22.000000
 
 
      In sections
      -----------
        VISB
 
 
      Description
      -----------
        Light flood is on, gain is low, and exposure offset is on.
 
 
    Instrument Mode 'LG.'
    =====================
      Gain Mode Id                   : HIGH
      Instrument Power Consumption   : 22.000000
 
 
      In sections
      -----------
        VISB
 
 
      Description
      -----------
        Light flood is on, gain is high, and exposure offset is off.
 
 
    Instrument Mode 'LGD'
    =====================
      Gain Mode Id                   : HIGH
      Instrument Power Consumption   : 22.000000
 
 
      In sections
      -----------
        VISB
 
 
      Description
      -----------
        Light flood is on, gain is high, and exposure offset is on.
 
 
    Mounted On Platform 'SCAN PLATFORM'
    ===================================
      Cone Offset Angle              : -0.032000
      Cross Cone Offset Angle        : 0.681000
      Twist Offset Angle             : 90.070000
 
 
      Description
      -----------
        (see Wellman et al, 1976)