20.22.21      SHORT_SD_FACTOR

REAL multiplicative calibration factor; it is used to convert from the single dish map units (e.g., main-beam brightness temperature) to janskys.

A default value of 0 can be used if the original data file is in unit of Tmb, the main beam brightness temperature, because in this case the conversion factor can be derived from the beam size. UV_SHORT will complain if it cannot derive the appropriate value.