Abstract
Time variability is commonly observed in the most compact extragalactic radio sources. Low-frequency variability (LFV)—at frequencies <1 GHz—is thought to arise through two different mechanisms, intrinsic and extrinsic. The former is just an extension of the often rapid high-frequency variations, delayed and reduced in amplitude. The latter is usually attributed to refractive interstellar scintillation (RISS; Rickett et al. 1984), whereby the variations in intensity are the result of wavefront distortions caused by transverse gradients in electron density. If RISS arises predominantly along the signal path through our Galaxy, we might expect to find evidence for a dependence on Galactic coordinates.
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© 1996 International Astronomical Union
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Hunstead, R.W., Gaensler, B.M. (1996). Long-Term Variability of Extragalactic Sources at 843 MHZ. In: Ekers, R., Fanti, C., Padrielli, L. (eds) Extragalactic Radio Sources. International Astronomical Union, vol 175. Springer, Dordrecht. https://doi.org/10.1007/978-94-009-0295-4_42
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DOI: https://doi.org/10.1007/978-94-009-0295-4_42
Publisher Name: Springer, Dordrecht
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