^a The wavelengths reported in the first column are the nominal wavelengths of each instrument waveband. The minimum and maximum wavelengths reported in the second and third columns correspond to a system response (filter+detector) equal to 10% of the maximum. In particular, the system response functions were taken for Spitzer/IRAC rom http://ssc.spitzer.caltech.edu/irac/spectral_response.html, for Spitzer/MIPS from http://ssc.spitzer.caltech.edu/mips/MIPSfiltsumm.txt, for COBE/DIRBE from http://lambda.gsfc.nasa.gov/data/cobe/dirbe/ancil/spec_resp/DIRBE_SYSTEM_SPECTRAL_RESPONSE_TABLE.ASC, for IRAS from http://irsa.ipac.caltech.edu/IRASdocs/exp.sup/ch2/tabC5.html, for MSX/SpiritIII from http://irsa.ipac.caltech.edu/data/MSX/docs/MSX_psc_es.pdf (Appendix A, Table A-3), for ISO/ISOPHOT from http://www.mpia.de/ISO/welcome.html; ^b uncertainties in this table have been taken directly from the literature when available. For COBE measurements, we assumed an error equal to 20% of the measured flux in each band as suggested by Odenwald et al. (1998) and for IRAS measurements equal to 15% as suggested by Rice et al. (1988). For our own measurements, the uncertainties have been derived as detailed in the text.