Fundamental physical constants characterizing black body radiation. The first radiation constant is \(c_{1} = 2\ \pi \ h\ c_{0}^{2}=3.741\,7749(22)\times 10^{-16}\ \text{W m}^{2}\), the second is \(c_{2} = \frac{h\ c_{0}}{k}=1.438\,769(12)\times 10^{-2}\ \text{m K}\), where \(h\) is the @P04685@ \(c_{0}\) the speed of light and \(k\) the @B00695@.