• Valerie Illingworth
Part of the Macmillan Dictionary Series book series (DICTS)


jansky. Symbol: Jy. The unit of *flux density adopted by the IAU in 1973 and used throughout the spectral range, especially for radio and far-infrared measurements. One jansky is equal to 10−26 watts per metre squared per hertz. It is possible to calculate the equivalent flux density, F(v), in jansky from a value of *mag- nitude at the effective wavelength, λeff, appropriate to a particular optical or infrared filter (see table). For example, an R magnitude of 3.2 corresponds to a flux density at 0.7 μ of
$${\text{2770x1}}{{\text{0}}^{{\text{ - 0}}{\text{.4x3}}{\text{.2}}}}{\text{Jy}}$$
i.e. 145 Jy. (The table gives the flux level for 0.0 magnitude.)


Methane Phosphorus Convection Mercury Helium 


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© Laurence Urdang Associates Ltd 1979

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  • Valerie Illingworth

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