Scintillation Arcs in Pulsar B0450–18

We report on Green Bank Telescope observations of interstellar scintillation from the pulsar B0450−18 at 340 and 825 MHz, revealing prominent arcs in secondary spectra both frequencies. The are successfully modeled by one-dimensional angular brightness distributions, estimated two independent techniques. distributions do not follow expected shape for a Kolmogorov plasma density spectrum, their overall widths scaling law, versus frequency, that is slightly slower than inverse square law dispersion. They also exhibit discrete peaks cause occasional reverse sub-arcs. Over narrow (5%) frequency range these participate spreading, having positions fixed sky. However, evolve over wider frequencies cannot be traced to MHz. Our conclusions add further evidence widespread distribution highly localized regions with small-scale structure either elongated or flattened.