The drag_date.dat file is a text file containing nominal drag model ACC and estimated delta CONST_L data.

The file has one time epoch for each line with 19 fields:

1    2   3            4           5     6               7   8          9   10  11     12     13 14    15    16        17      18           19
Time sat nominal_drag delta_acc_l sigma nominal_density doy local_hour lat lon height A/Mass Cd speed sflux mean_flux mag_act mean_mag_act mag_dot

1. Time -- GPS second past J2000 (TDT second = Time + 51.184).
2. sat -- name of satellite.
3. nominal_drag -- acceleration value from DTM2000 model (nm/s/s), the value is negative to be consistent with next column.
4. delta_acc_l -- estimated acceleration CONST_L (nm/s/s) in along-track direction (total drag_acc = nominal_drag + delta_acc_l).
5. sigma -- formal sigma of delta_acc_l (nm/s/s).
6. nominal_density -- air density value from DTM2000 model in 1e-6*kg/km^3 ( 1 g/cm^3 = 1e3 kg/m^3 = 1e12 kg/km^3)
7. doy -- day-of-year for the time (may be relpaced by Sun's latitude later).
8. local_hour -- local time in hour (may be replaced by Sun's longitude later).
9. lat -- latitude of satellite (degree).
10. lon -- longitude of satellite (degree).
11. height -- height of satellite (km).
12. A/Mass -- effective profile area over mass (m^2/kg).
13. Cd -- nominal Cd valued used to compute drag from density.
14. speed -- satellite speed used to compute drag from density (km/s).
15. sflux -- Solar flux used by DTM2000 model to compute density (1.E-22 watts/m^2/cycles/second/bw).
16. mean_flux -- 81 day average solar flux.
17. mag_act -- geomagnetic activity used by DTM2000 model to compute density.
18. mean_mag_act -- 24-hour average of mag_act used by DTM2000 model.
19. mag_dot -- time derivative of mag_act.

Note: 
  with the assigned unit for each column above, the calculation of drag is straight forward without scaling:

  column_3 = 0.5*column_6*column_12*column_13*column_14^2

  to convert the drag and delta_acc_l data into unified density data using an unified Cd0 value (for all days):

  Density = -2.0*(column_3+column_4)/(Cd0*column_12*column_14^2)

  and the O-C in density is (with an unknown scale in Cd0):

  O-C = Density - column_6

Example:
 302356800 GRACEA    -6.3578     1.8314    8.7    57.3832 212.96   3.00 -35.572   46.631    468.593    0.00252    1.50810    7.63734    68.1745 69.0000     1.0000     1.3131  0.000000e+00
 302357100 GRACEA    -8.0353     0.9990    8.8    70.8709 213.00   3.03 -16.308   45.789    463.473    0.00257    1.50810    7.64382    68.1780 69.0000     1.0000     1.3166  0.000000e+00
 302357400 GRACEA    -8.7727     0.3919    8.8    76.9295 213.00   3.05 2.996   44.872    462.181    0.00259    1.50810    7.64549    68.1780 69.0000     1.0000     1.3200  0.000000e+00