FILENAME: igrfgen1.dat.
Coefficients of original (1st generation) IGRF. Adopted at the Symposium
on "The Description of the Earth's Magnetic Field", Washington, D.C.,
1968 October.
REFERENCE: Zmuda, A. J., 1971. "The International Geomagnetic Reference
Field: introduction", Bull. Int. Assoc. Geomagn. Aeron., No. 28, 148-152.
The coefficients for each constituent model, as given below, are in the order
g01, g11, h11, g02, g12, h12, g22, h22, ....., gn*n*, hn*n*.
Main-field model for 1965; secular-variation model for 1965-75, both to n* = 8.
PROGRAM: the Fortran subroutine IGRF contains the coefficients of this 1st
generation IGRF in DATA statements.  A listing of the source code of IGRF
(as well as a listing of the Algol procedure IGRF which lists the coefficients
in a 'comment' statement) has been published in Barraclough, D. R. & Malin,
S. R. C., 1971.  "Synthesis of International Geomagnetic Reference Field 
Values", Rep. Inst. Geol. Sci., No. 71/1.
Main-field model for 1965.0:
 -30339.  -2123.   5758.  -1654.   2994.  -2006.   1567.    130.   1297.  -2036.
   -403.   1289.    242.    843.   -176.    958.    805.    149.    492.   -280.
   -392.      8.    256.   -265.   -223.    357.     16.    246.    125.    -26.
   -123.   -161.   -107.    -51.     77.     47.     60.    -14.      4.    106.
   -229.     68.      3.    -32.     -4.    -10.   -112.    -13.     71.    -54.
    -57.      0.    -27.     12.     -8.    -25.      9.     -9.     23.     13.
    -19.     -2.    -17.     10.      9.      3.     -3.    -13.    -12.      5.
     -4.    -17.      7.      4.     -5.     22.     12.     -3.      6.    -16.
Secular-variation model for 1965-75:
    15.3     8.7    -2.3   -24.4     0.3   -11.8    -1.6   -16.7     0.2   -10.8
     4.2     0.7     0.7    -3.8    -7.7    -0.7     0.2    -0.1    -3.0     1.6
    -0.1     2.9    -2.1    -4.2     1.9     1.1     2.3     2.9     1.7     0.6
    -2.4     0.0     0.8     1.3    -0.3    -0.1    -0.3    -0.9     1.1    -0.4
     1.9     2.0    -0.4    -1.1    -0.4     0.1    -0.2     0.9    -0.5    -0.3
    -1.1    -0.7     0.3    -0.5     0.4     0.3     0.2     0.0     0.4    -0.2
     0.2    -0.6     0.3     0.1     0.4     0.1     0.6    -0.2     0.0    -0.3
     0.0    -0.2    -0.1    -0.3     0.3    -0.4    -0.3    -0.3    -0.5    -0.3