----------------------------------------------------------------------------
DATA SET:  MGN V RDRS 5 GLOBAL DATA RECORD TOPOGRAPHIC V1.0
 
  Data Set Information
  ====================
  Processing Level Id            : 5
  Data Set Name                  : MGN V RDRS 5 GLOBAL DATA RECORD TOPOGRAPHIC V1.0
  Start Time                     : 1990-09-13T16:22:14.871
  Stop Time                      : 1994-01-12
  Data Object Type               : IMAGE
  Data Set Release Date          : 1992-01-15
  Producer Full Name             : PETER G. FORD
  Producer Institution Name      : MASSACHUSETTS INSTITUTE OF TECHNOLOGY
  Software Flag                  : N
  Detailed Catalog Flag          : N
  Processing Start Time          : 1991-03-27T16:00:15
  Processing Stop Time           : UNK
  Data Set Collection Member Flg : N
 
  Processing Level Description
  ============================
    Derived Data - Derived results, as maps, reports, graphs,
    etc. NASA levels 2 through 5.
 
  Data Set Processing
  ===================
    Source Data Set Id             : MGN-V-RDRS-5-CDR-ALT/RAD-V1.0
    Software Name                  : MGMMAP
    Cognizant Full Name            : PETER G. FORD
 
    Description
    -----------
      The MIT Altimetry and Radiometry Mapping Software (MGMMAP)
      reads Altimetry and Radiometry Composite Data Records
      (ARCDRs), and generates an image of a specified data field i
      a specified map projection. Each footprint datum is added
      with a weight and horizontal extent proportional to the
      appropriate ARCDR elements. This software will be released t
      Magellan Data Management Archive Team (DMAT) upon the
      completion of the nominal mission.
 
  Associated Targets
  ==================
    VENUS
 
  Associated Instruments
  ======================

    Host:        MAGELLAN (MGN)
    Instrument:  RADAR SYSTEM (RDRS)
 
  Parameter Information
  =====================

    Data Set Parameter: PLANETARY RADIUS
    ---------------------------------
      Sampling Parameter: PIXEL
 
      Description
      -----------
        Radial distance from center of planet or satellite to given
        location on the surface.
 
  Data Set Description
  ====================
    Global Topographic Data Record (GTDR). The range to surface
    is derived by fitting altimeter echoes from the fan-beam
    altimetry antenna as a function of time to Hagfors' radar
    backscatter model templates. The ranges are subtracted from
    the spacecraft radial coordinate (derived from Doppler
    tracking), yielding measurements of planetary radius. The
    data are filtered to remove low-frequency errors in the
    in-plane elements of each spacecraft orbit, and then
    re-sampled into sinusoidal, Mercator, and north and south
    polar stereographic projections at a resolution of about 5x5
    kilometers per pixel. A fifth image contains estimates of
    the absolute accuracy of the radius values in each pixel of
    the sinusoidal projection. This is derived by taking the
    root mean square of (a) the statistical accuracy anticipated
    from the template fitting and (b) the systematic errors
    estimated from the in-plane element filtration. Note that
    this is the absolute topographic accuracy -- relative errors
    are much smaller, about 10-15 meters in relatively flat
    areas.
     
    Except in the radius error image, each GTDR pixel is
    represented by a 16-bit integer. In sinusoidal images,
    pixels lying outside the domain of the projection are set to
    zero. In all images, pixels with unknown or unmeasured
    values are also set to zero. The remaining values are
    related to the planetary radius by the following equation:
     
          DN = (RADIUS <METERS>) - 6039999
     
    In the radius error image, each pixel is represented by an
    8-bit integer. Pixels lying outside the domain of the
    projection are set to zero, as are all pixels with unknown
    or unmeasured values. The remaining values are related to
    the radius error by the following equation:
     
          DN = (RADIUS-ERROR <METERS> * 0.2) + 1
     
    See: Software Interface Specification Document (Peter G.
    Ford, 1991, Global Altimetry and Radiometry Data Records,
    MIT-MGN-GxDR SIS Version 2.3, 40 p.) that is included on
    GxDR CD-ROMs.
     
     
    Note: There exist photoproducts that are identified as GxDRP
    (where x is E (Emissivity), S (Slope), RE (Reflectivity), or
    T (Topography)) however, they are not generated from the
    digital GxDR products. They are instead produced from the
    Magellan ARCDR (Altimetry and Radiometry Composite Data
    Record) data files.
 
  Confidence Level Note
  =====================
    UNK
 
  Reference
  =========
    Journal:          PROJECT MAGELLAN SIS DOCUMENT
    Publication Date: 1991-01-01
    Reference Key ID: FORD1991
 
    Authors
    -------
      PETER G. FORD
 
    Citation
    --------
      Peter G. Ford, Global Altimetry and Radiometry Data Record,
      Project Magellan Software Interface Specification Document
      MIT-MGN-GxDR, 1991 Version 2.3, 40p.
 
  Reference
  =========
    Journal:          JOURNAL OF GEOPHYSICAL RESEARCH
    Publication Date: 1990-01-01
    Reference Key ID: SAUNDERSETAL1990
 
    Authors
    -------
      GORDON H. PETTENGILL
      LESLIE J. PIERI
      R. STEPHEN SAUNDERS
      RAYMOND E. ARVIDSON
      W. L. SJOGREN
      WILLIAM T. K. JOHNSON
 
    Citation
    --------
      Saunders, R.S., G.H. Pettengill, R.E. Arvidson, W.L.
      Sjogren, W.T.K. Johnson, L. Pieri, The Magellan Venus Radar
      Mapping Mission, Journal of Geophysical Research, 1990, Vol
      95, pp. 8339-8335
 
  Inventory Information
  =====================
 
    Available on CD-ROM - "USA_NASA_JPL_MG_3001"
    --------------------------------------------
    Node Id                        : NSSDC
    Volume Series Name             : MISSION TO VENUS
    Volume Set Name                : MAGELLAN: GLOBAL ALTIMETRY AND RADIOMETRY DATA
    Volumes                        : 1
    General Catalog Flag           : Y
