PDS_VERSION_ID               = PDS3
RECORD_TYPE                  = FIXED_LENGTH
RECORD_BYTES                 = 122
FILE_RECORDS                 = 4188    
^SHADR_HEADER_TABLE          = ("GTM090AA.SHA",1)              
^SHADR_COEFFICIENTS_TABLE    = ("GTM090AA.SHA",3)              
INSTRUMENT_HOST_NAME         = "MARS GLOBAL SURVEYOR"
TARGET_NAME                  = MARS
INSTRUMENT_NAME              = "MARS ORBITER LASER ALTIMETER"
DATA_SET_ID                  = "MGS-M-MOLA-5-SHADR-V1.0"
OBSERVATION_TYPE             = "TOPOGRAPHY MODEL"
ORIGINAL_PRODUCT_ID          = "mars.shape"                            
PRODUCT_ID                   = "GTM090AA.SHA"
PRODUCT_RELEASE_DATE         = 2000-12-31
DESCRIPTION                  = "
 
 This file contains coefficients and related data for a spherical 
 harmonic model of the shape of Mars.  Input data are from the Mars
 Orbiter Laser Altimeter (MOLA) on the Mars Global Surveyor (MGS)
 spacecraft.  Coordinate system is IAU 1991 (Davies et al., 
 Celestial Mechanics and Dynamical Astronomy, 53, 377-397, 1992),
 areocentric, with longitudes measured positive east.  When 
 evaluated, the model gives absolute radius from Mars center of
 mass in meters.
 
 The model is a numerical transform of planetary radius values
 from the MOLA 0.5-degree gridded data set        
            DATA_SET_ID = 'MGS-M-MOLA-5-IEGDR-L3-V2.0'
            PRODUCT_ID  = 'MOLA-IEG0062R.IMG'
 into spherical harmonics using Simpson's Rule quadrature.
 
 The gridded data set included all MOLA nadir observations from the
 Orbit Insertion phase, plus Mapping Phase nadir observations from
 the beginning of mapping through the end of December 1999. 
 Additionally, off-nadir observations of the north pole were
 included from 87 N latitude and northward, taken during the spring
 of 1998, and of both poles taken in July of 1999, from 87 N and S 
 to the poles.  Orbits 355 and 358 of the Orbit Insertion Phase 
 and parts of orbits 10709 through 10716, inclusive, of the Mapping
 Phase were excluded because solutions for these orbits were deemed
 to be poor. (Note: subtract 10000 from a MOLA mapping phase orbit 
 number to determine the equivalent MGS Project orbit number.) 
 Also excluded were shots more than 1 degree off-nadir except as 
 noted above), channel 4 returns, and any returns not classified 
 as ground returns, e.g. clouds or noise, according to the
 SHOT_CLASSIFICATION_CODE. A total of approximately 123 million
 observations are represented.
 
 Further improvements to the model are expected as additional MGS 
 data are incorporated.                       
 
 This product is a set of two ASCII tables: a header table and a 
 coefficients table.  Definitions of the tables follow.    
 
 This Mars topography model was produced under the direction of 
 D.E. Smith of the MGS MOLA Team."                

START_TIME                   = 1997-09-15T19:10:00
STOP_TIME                    = 1999-12-31T23:59:59
PRODUCT_CREATION_TIME        = 2000-11-16T00:00:00
PRODUCER_FULL_NAME           = "GREG NEUMANN"                          
PRODUCER_INSTITUTION_NAME    = "GODDARD SPACE FLIGHT CENTER"
PRODUCT_VERSION_TYPE         = "PRELIMINARY"                 
PRODUCER_ID                  = "MGS MOLA"
SOFTWARE_NAME                = "UNK;UNK"                               

OBJECT               = SHADR_HEADER_TABLE
ROWS                       = 1
COLUMNS                    = 8
ROW_BYTES                  = 137
ROW_SUFFIX_BYTES           = 107
INTERCHANGE_FORMAT         = ASCII
DESCRIPTION                = "The SHADR header includes descriptive
 information about the spherical harmonic coefficients which follow
 in SHADR_COEFFICIENTS_TABLE.  The header consists of a single record
 of eight (delimited) data columns requiring 137 bytes, a pad of 105 
 unspecified ASCII characters, an ASCII carriage-return, and an ASCII
 line-feed."

  OBJECT                   = COLUMN
    NAME                         = "REFERENCE RADIUS"
    DATA_TYPE                    = ASCII_REAL
    START_BYTE                   = 1
    BYTES                        = 23
    FORMAT                       = "E23.16"
    UNIT                         = "KILOMETER"
    DESCRIPTION                  = "A nominal value for the
     equatorial radius.  The model gives absolute radius directly,
     so REFERENCE RADIUS is not needed when using the model."
  END_OBJECT               = COLUMN

  OBJECT                   = COLUMN
    NAME                         = "CONSTANT"
    DATA_TYPE                    = ASCII_REAL
    START_BYTE                   = 25
    BYTES                        = 23
    FORMAT                       = "E23.16"
    UNIT                         = "N/A"
    DESCRIPTION                  = "For a gravity field model the
     assumed gravitational constant GM in km cubed per seconds
     squared for the planet.  For a topography model, set to 1."
  END_OBJECT               = COLUMN

  OBJECT                   = COLUMN
    NAME                         = "UNCERTAINTY IN CONSTANT"
    DATA_TYPE                    = ASCII_REAL
    START_BYTE                   = 49
    BYTES                        = 23
    FORMAT                       = "E23.16"
    UNIT                         = "N/A"
    DESCRIPTION                  = "For a gravity field model the
     uncertainty in the gravitational constant GM in km cubed per
     seconds squared for the planet (or, set to 0 if not known).
     For a topography model, set to 0."
  END_OBJECT               = COLUMN

  OBJECT                   = COLUMN
    NAME                         = "DEGREE OF FIELD"
    DATA_TYPE                    = ASCII_INTEGER
    START_BYTE                   = 73
    BYTES                        = 5
    FORMAT                       = "I5"
    UNIT                         = "N/A"
    DESCRIPTION                  = "Degree of the model field."
  END_OBJECT               = COLUMN

  OBJECT                   = COLUMN
    NAME                         = "ORDER OF FIELD"
    DATA_TYPE                    = ASCII_INTEGER
    START_BYTE                   = 79
    BYTES                        = 5
    FORMAT                       = "I5"
    UNIT                         = "N/A"
    DESCRIPTION                  = "Order of the model field."
  END_OBJECT               = COLUMN

  OBJECT                   = COLUMN
    NAME                         = "NORMALIZATION STATE"
    DATA_TYPE                    = ASCII_INTEGER
    START_BYTE                   = 85
    BYTES                        = 5
    FORMAT                       = "I5"
    UNIT                         = "N/A"
    DESCRIPTION                  = "The normalization indicator.
     For gravity field:
        0   coefficients are unnormalized
        1   coefficients are normalized
        2   other."
  END_OBJECT               = COLUMN

  OBJECT                   = COLUMN
    NAME                         = "REFERENCE LONGITUDE"
    POSITIVE_LONGITUDE_DIRECTION = "EAST"
    DATA_TYPE                    = ASCII_REAL
    START_BYTE                   = 91
    BYTES                        = 23
    FORMAT                       = "E23.16"
    UNIT                         = "DEGREE"
    DESCRIPTION                  = "The reference longitude for the
     spherical harmonic expansion; normally 0."
  END_OBJECT               = COLUMN

  OBJECT                   = COLUMN
    NAME                         = "REFERENCE LATITUDE"
    DATA_TYPE                    = ASCII_REAL
    START_BYTE                   = 115
    BYTES                        = 23
    FORMAT                       = "E23.16"
    UNIT                         = "DEGREE"
    DESCRIPTION                  = "The reference latitude for the
     spherical harmonic expansion; normally 0."
  END_OBJECT               = COLUMN

END_OBJECT           = SHADR_HEADER_TABLE

OBJECT               = SHADR_COEFFICIENTS_TABLE
  ROWS                     = 4186
  COLUMNS                  = 6
  ROW_BYTES                = 107
  ROW_SUFFIX_BYTES         = 15
  INTERCHANGE_FORMAT       = ASCII
  DESCRIPTION              = "The SHADR coefficients table contains
   the coefficients for the spherical harmonic model. Each row in the
   table contains the degree index m, the order index n, the 
   coefficients Cmn and Smn, and the uncertainties in Cmn and Smn.
   The (delimited) data require 107 ASCII characters; these are
   followed by a pad of 13 unspecified ASCII characters, an ASCII
   carriage-return, and an ASCII line-feed.  When evaluated, the
   model gives absolute radius from Mars center of mass in meters."

  OBJECT                   = COLUMN
    NAME                         = "COEFFICIENT DEGREE"
    DATA_TYPE                    = ASCII_INTEGER
    START_BYTE                   = 1
    BYTES                        = 5
    FORMAT                       = "I5"
    UNIT                         = "N/A"
    DESCRIPTION                  = "The degree index m of the
    C and S coefficients in this record."
  END_OBJECT               = COLUMN

  OBJECT                   = COLUMN
    NAME                         = "COEFFICIENT ORDER"
    DATA_TYPE                    = ASCII_INTEGER
    START_BYTE                   = 7
    BYTES                        = 5
    FORMAT                       = "I5"
    UNIT                         = "N/A"
    DESCRIPTION                  = "The order index n of the C and S
     coefficients in this record."
  END_OBJECT               = COLUMN

  OBJECT                   = COLUMN
    NAME                         = "C"
    DATA_TYPE                    = ASCII_REAL
    START_BYTE                   = 13
    BYTES                        = 23
    FORMAT                       = "E23.16"
    UNIT                         = "N/A"
    DESCRIPTION                  = "The coefficient Cmn for this 
     spherical harmonic model."
  END_OBJECT               = COLUMN

  OBJECT                   = COLUMN
    NAME                         = "S"
    DATA_TYPE                    = ASCII_REAL
    START_BYTE                   = 37
    BYTES                        = 23
    FORMAT                       = "E23.16"
    UNIT                         = "N/A"
    DESCRIPTION                  = "The coefficient Smn for this
     spherical harmonic model."
  END_OBJECT               = COLUMN

  OBJECT                   = COLUMN
    NAME                         = "C UNCERTAINTY"
    DATA_TYPE                    = ASCII_REAL
    START_BYTE                   = 61
    BYTES                        = 23
    FORMAT                       = "E23.16"
    UNIT                         = "N/A"
    DESCRIPTION                  = "The uncertainty in the coefficient
     Cmn for this spherical harmonic model."
  END_OBJECT               = COLUMN

  OBJECT                   = COLUMN
    NAME                         = "S UNCERTAINTY"
    DATA_TYPE                    = ASCII_REAL
    START_BYTE                   = 85
    BYTES                        = 23
    FORMAT                       = "E23.16"
    UNIT                         = "N/A"
    DESCRIPTION                  = "The uncertainty in the coefficient
     Smn for this spherical harmonic model."
  END_OBJECT               = COLUMN

END_OBJECT           = SHADR_COEFFICIENTS_TABLE

END
