FUNCSPEC
-- time (yr)  gravmtz (mcGal) at x=0, z=0
    0.0         0.0
    0.25        3.75563
    0.5         8.33386
    0.75        12.9117
    1           16.3967
    1.25        18.1877
    1.5         18.0155
    1.75        14.6973
    2           6.64664
    2.25       -3.4142
    2.5        -14.4789
    2.75       -25.7217
    3          -36.5741
    3.25       -46.7229
    3.5        -56.0867
    3.75       -64.6171
    4          -72.2306
    4.25       -78.9296
    4.5        -84.7963
    4.75       -89.8235
    5          -94.0429
    5.25       -97.5447
    5.5        -100.362
    5.75       -102.513
    6          -104.042
    6.25       -104.993 
    6.5        -105.391
    6.75       -105.289
    7          -104.727
    7.25       -103.746
    7.5        -102.376
    7.75       -100.666
    8          -98.677
    8.25       -96.4445
    8.5        -94.0078
    8.75       -91.4062
    9          -88.6895
    9.25       -85.8868
    9.5        -83.0321
    9.75       -80.1576
   10          -77.2846
/