Regarding the 3333 tie file:
  • A virtual check-in was created for the begining of the day, because another
    gravity check-in point was used and not visited again. To do this:
      – A Δ from datum value was calculated for the check-in used at the 
        begining of the day:
          ○ station 2222
          ○ datum                          7377.834 mGal
          ○ early  day value             – 5521.918 mGal
          ○ Δ                            = 1855.916 mGal.
      – The Δ value was then subtracted from the datum of 3333 to create 
        a virtual check-in at the time of the 2222 check-in:
          ○ station 3333
          ○ datum                          7335.710 mGal
          ○ Δ                            – 1855.916 mGal        
          ○ virtual check-in             = 5479.794 mGal

Regarding the 2 xyz files:
  • The DEM covering the whole area is very large, in fact likely too large for
    the field computer used in conjunction with Gravred 3.2 (who is systematically
    loading the whole DEM to the RAM before proceeding to calculations). So in order
    to avoid errors due to lack of memory available, the inner DEM was split into
    2 files of 5.5M points each, and the results from two individual runs are added
    together to create the final xyz containing one unique inner DEM correction value.
  • The final xyz is actually a merger of all days together.