ISO/TC 211 Multi-Lingual Glossary of Terms (MLGT)

Note 1 to entry: This radiation is understood to be the radiation emitted by the universe at an early period of its history.

Note 2 to entry: In order to use CMB for calibrating a microwave radiometer operating at microwave to submillimetre band, it should be converted into brightness temperature, ${\displaystyle T_{\text{B}}}$ , according to the following formula:${\displaystyle T_{\text{B}}=\frac{\text{h}\nu (e^{\frac{\text{h}\nu }{\text{k}{T}_{\text{c}}}}+1)}{2\text{k}(e^{\frac{\text{h}\nu }{\text{k}{T}_{\text{c}}}}-1)}}$ where ${\displaystyle \text{h}}$ is the Planck’s constant (${\displaystyle 6.62607\times {10}^{-34}\text{J}\cdot \text{s}}$ ); ${\displaystyle v}$ is the frequency in Hz; ${\displaystyle \text{k}}$ is the Boltzmann’s constant (${\displaystyle 1.38064852\times {10}^{-23}\text{J}/\text{K}}$ ); ${\displaystyle T_{\text{c}}}$ is the cosmic background temperature (${\displaystyle 2.736\pm 0.017\text{K}}$ ); ${\displaystyle \text{e}}$ is the base of natural logarithm