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Session 111 - Pulsars.
Display session, Saturday, January 10
We present flux density variations of the nearby pulsar B1929+10 at 3.6, 6, and 13cm observed with the 100m radio telescope at Effelsberg, Germany. The variations are partially correlated between the different wavelengths and have characteristic time scales of about 30 minutes and modulation indices increasing with wavelength from 0.1 to 0.7. We interpret the variations as weak interstellar scintillations and compare them with theory based on models for the spectrum and spatial distribution of the interstellar plasma density. In weak scintillation, the intensity spectrum is equal to the plasma density spectrum times a high pass filter, which depends slowly on the spatial distribution. We consider the Kolmogorov spectrum model with and without an inner scale cut-off and we model the spatial distribution as either concentrated in a thin layer or uniformly extended along the line of sight. The theoretical structure functions for intensity fluctuations are fitted to the structure functions estimated from the measurements and used to constrain the model parameters.
Program listing for Saturday