In this method, source counts are taken from the analytic fits to infrared galaxy counts (Soifer et al., 1987) and are extrapolated to two sets of functions of source counts vs. limiting flux. Each set contains functions computed for wavelengths which cover the ISO wavelengths range). The two sets of functions differ in that each set is computed under a different cosmological model so as to bracket the results of the calculation. The program finds the smallest flux at which the flux variance of the faint source background will contribute an uncertainty of less than 20%, and equates this variance to the confusion noise. The two bracketing cosmological models are: Model 1: q0=0.5, H0=100, and source density~(1+z)^5; and Model 2: Euclidean.
REFERENCES: Desert, F-X., Boulanger, F., and Puget, J., 1990, Interstellar Dust Models for Extinction and Emission, A & A 237, 215. Gautier, T. N. et al. 1992, A Calculation of Confusion Noise Due to Infrared Cirrus, AJ, 103 1313. [provides details of the cirrus confusion calculation] Helou and Beichman 1990, Proc. 29, Liege Intn. Astr. Coll., ESA SP 314. [provides an overview of the cirrus confusion calculation] This paper is online in PostScript form on IPAC's publicftp machine: ftp.ipac.caltech.edu in /pub/irsky/doc Look for the files: helou_beichman.ps helou_beichman_figure1.ps helou_beichman_figure2.ps helou_beichman_figure3.ps helou_beichman_figure4.ps