Intraday Radio Variability and Micro-Arcsecond Resolution

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Citation of Original Publication

Bignall, Hayley E.; Jauncey, David L.; Kedziora-Chudczer, Lucyna; Lovell, James E. J.; Macquart, Jean-Pierre; Ojha, Roopesh; Rickett, Barnaby J.; Intraday Radio Variability and Micro-Arcsecond Resolution; Approaching Micro-Arcsecond Resolution with VSOP-2: Astrophysics and Technology; ASP Conference Series, Vol. 402, ©2009;


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Intraday variability (IDV) of AGN at centimeter wavelengths has been shown to be predominantly due to interstellar scintillation (ISS). Recent VLBI observations have shown that IDV sources are more compact than non-IDVs on milliarcsecond scales, and a significant fraction are completely unresolved with ground-based VLBI. Additionally, very rapid IDV due to ISS has been observed in some extragalactic water masers at 22 GHz, implying masers ∼ 10 micro-arcseconds in angular size. Such bright, compact sources will be excellent targets for observation with VSOP-2 in order to study the sub-pc scale regions of AGN.