NSA/MWR/C1 - software upgrade (version 3.28)
The MWR operating program was upgraded to version 3.28 on 3 February 1999. This version includes a beam width correction as well as providing the capability to automatically level the elevation mirror (that is, to automatically detect and correct offsets in the elevation angle stepper motor position.) The improvement in the quality of the tip curves resulting from the auto- leveling has been dramatic: differences in the brightness temperatures at 3 airmasses (19.5 and 160.5 degrees) have been reduced from +/- 5 K to +/- 0.5 K. In order to take full advantage of this improvement to detect and reject cloudy tip curves, the minimum value of the goodness-of-fit coefficient for a valid tip curve has been increased from 0.995 to 0.998.
The data prior to this date do not include beam-width and mirror-leveling corrections.