Scintillation Properties of PSR B1133+16 Measured with Very Long Baseline Interferometry

The scintillation of pulsars reveals the small-scale structure of the interstellar medium. A powerful technique for characterizing the scintillating structures (screens) combines analysis of scintillation arcs and very long baseline interferometry (VLBI). We present the results of a VLBI analysis of the scintillation arcs of PSR B1133+16 from simultaneous observations with Arecibo, Very Large Array, Jodrell Bank, Effelsberg, and Westerbork. Three arcs appear in the dataset, all of which appear consistent with being the result of very anisotropic scattering screens. We are able to measure their orientations on the sky, down to uncertainties of 5° for the two stronger screens, and measure distances of 140 ± 30, 180 ± 20, and 250 ± 30 pc, consistent with, but substantially more precise than what was inferred previously from annual modulation patterns in the scintillation. Compared with the differential dust extinction with distance in this direction, the two nearer screens appear associated with the wall of the Local Bubble.