The figure above shows the WISE response per photon. It should be the quantum efficiency times the transmission of the optics, beamsplitters and filters. Data files containing the wavelength in microns, the response, and the uncertainty in the response in parts per thousand are available for W1, W2, W3 and W4. These Relative Spectral Response curves were constructed from measurements of the whole system supplemented by component measurements and the expected value from the design. The latter two are assumed to have a relative error of 1000 parts per thousand, while the end-to-end measurements can have higher weight if there was adequate SNR in the calibration setup.
For a signal with a spectrum having ν Fν =
const, the effective wavelengths of the four bands are given
by 3.368, 4.618, 12.082 and 22.194 μm.
The effective wavelength is defined such that infinitesimal power law
changes to the spectrum, pivoting about the effctive wavelength, do not
change the integrated response:
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