Final user takes SEFD = Tsys / DPFU

or simply original Fsys

Thus, DPFU is just a scaling factor completely irrelevant to calibration quality

Ø Any change of DPFU would not influence SEFD

Ø Changes of DPFU reflect in Tcal and Tsys only

Ø Attempts to fit DPFU are useless, hence they create confusion

The question of Polynomial normalization

Poly is used to correct source power Fso for the component of atmospheric opacity and antenna efficiency that depends on the elevation.
Poly is usually normalized to unity at its maximum, which means not well specified elevation.
Thus, in general, every station normalizes their equivalent flux density to different atmosphere.
It would be better to set it to 1 at zenith where all stations see similar atmospheric opacity.

Concluding points

v     Disable GNPLT option to fit DPFU

v     Update GNPLT to fit gain curve alone (normalized at zenith)

v     For us, calibration friends, it would serve better if we adopted the equivalent flux densities for primary working quantities instead of the intermediate noise temperatures