As part of the ATESE project, Tuntsov et al. took data with the Compact
Array on the quasar PMN J1106-3607. Large variations in the flux density and
the spectrum were seen as shown in the Figure which shows (top) the entire
1000 day monitoring period and (bottom) a zoom-in of 100 days worth. Tuntsov
et al. interpret the variations as interstellar scintillation, both diffractive
and refractive, of a source that is compact but not point-like. The scattering
material is only some 50 pc distant and has a sharp concave boundary.