IRAS Explanatory Supplement
VI. Flux Reconstruction and Calibration
C. Absolute Calibration
C.1 General Philosophy
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The spectral response of the bands is sufficiently broad (Section II.C.2) that it is necessary to specify the continuum energy distribution of the source being observed when defining flux densities at a given wavelength. The approach used for IRAS was to assign effective wavelengths of 12, 25, 60 and 100 µm for the four bands. The effective bandwidth of each band was then calculated such that the quoted flux densities are correct if the source has an energy distribution with a flux per logarithmic frequency interval v × fv = × f which is constant with frequency . Any other continuum distribution, and in particular that of hot stars, requires a color correction. This color correction, which ranges up to 50% for astronomically interesting continua, is discussed in detail in Section VI.C.3 below.
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