radiation constants

Fundamental physical constants characterizing black body radiation. The first radiation constant is $c 1 = 2 π h c 0 2 = 3.741 7749 22 × 10 −16 W m 2$ , the second is $c 2 = h c 0 k = 1.438 769 12 × 10 −2 m K$ , where $h$ is the Planck constant $c 0$ the speed of light and $k$ the Boltzmann constant.

Source:

CODATA Bull. 1986, 63, 1