There are two files included on this CD:

1.) elv3s.dtm  
   -- This file is the 3 by 3 arc-second elevation model used for
      producing residual terrain model effetcts. It is in 
      "scanline" format with the first line defining the 
      geographic extent of the terrain model at the exact data 
      locations given as :

 south limit(deg)  north limit(deg)  west limit(deg)  
   east limit(deg) latitude increment(deg) longitude increment(deg)

      The rest of the file is the elevation values arranged in north
      to south latitude bands a 3 arc-second band at a time with 
      longitudes in 3 second increments from from west to east.

      There are a total of 6000 X 9600 = 57,600,000 elevation 
      values.

2.) ptfa.gs
   -- This file is the point free-air anomaly file for 53,149 
      points covering a geographic extent from 45 - 48 N, 5 - 11 E.
      Each line represents one free-air location and is given as:

      index  latitude(deg)  longitude(deg)  elevation(meters)
                 free-air anomaly(mgals)  accuracy(mgals)

If there are any questions concerning these two files, please
contact me.



John Factor

NGA / PRGB (L-41)
3838 Vogel Rd.
Arnold, MO    63010

(314) 263-4422
e-mail: John.K.Factor@nga.mil