which is a $z=0.457$ spiral galaxy (Stern et al., in prep.). In order to estimate the systematic uncertainty associated with fitting the flux density of a faint source near a bright one, we performed a Monte-Carlo simulation. We identified a relatively isolated source in the mosaic with about the same flux density as the spiral galaxy: this is the galaxy at 3:32:43.49, -27:45:56.45 (J2000) which has a flux density of 121$\pm$10$\mu$Jy at 16$\mu$m. We added an artificial source at a distance between 7$\arcsec$ and 8$\arcsec$ from this source and extracted the flux density using the positional priors. The process was repeated 100 times each for a range of flux densities straddling the measured flux density of the source. The extracted flux was compared with the input flux density to assess the systematic uncertainty and/or flux bias in the measurement. For a source with a brightness comparable to JD2, the Monte-Carlo analysis yielded 1$\sigma$ uncertainties of 14$\mu$Jy, 12$\mu$Jy and 10$\mu$Jy at 16, 22 and 24[$\mu$m]{}, respectively. This systematic uncertainty is primarily due to the extended wings of the brighter source and is a factor of $\sim$2-3 larger than the statistical uncertainty. We therefore adopt values of 14$\pm$14$\mu$Jy at 16$\mu$m, 56$\pm$12$\mu$Jy at 