The statistical uncertainty of flux densities in the IRAS serendipitous survey

The statistical uncertainty in the flux densities reported in the IRAS Serendipitous Survey Catalog (1986) is analyzed by examining differences in the measurements of sources in two independent observations. An assessment of the statistical uncertainty as a function of flux density in the Catalog has been made by accumulating these differences for over 4000 sources spanning a brightness range from 0.05 to over 20 Jy. The functional forms of the relative uncertainties at 12, 25, 60, and 100 microns are presented.