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The brightness temperature  of a body is defined according to
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(1) |
where  is the specific intensity and  is given by the Planck Law. In radio astronomy,
the Rayleigh-Jeans law can be used to approximate the Planck Law, so
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(2) |
where has MKS units of
 ,
 is
the frequency, k is Boltzmann's constant, T is the physical temperature, and c is the speed of light.
 Antenna Temperature, Brightness, Planck Intensity Density, Planck Law, Specific Intensity
Janssen, M. A. "An Introduction to teh Passive Microwave Remote Sensing of Atmospheres."
Ch. 1 in Atmospheric Remote Sensing by Microwave Radiometry (Ed. M. A. Janssen).
New York: Wiley, pp. 1-35, 1993.
Rybicki, G. and Lightman, A. P. Radiative Processes in Astrophysics. New York: Wiley-Interscience, pp. 25-26, 1979.
Thompson, A. R.; Moran, J. M.; and Swenson, G. W. Jr. Interferometry and Synthesis in Radio Astronomy.
New York: Wiley, p. 8, 1986.
© 1996-2007 Eric W. Weisstein
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