Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Interstellar Scintillation od Pulsar B0809+74   Weak interstellar scintillations of pulsar B0809+74 were observed at two
epochs using a 30m EISCAT antenna at 933 MHz. These have been used to constrain
the spectrum, the distribution and the transverse velocity of the scattering
plasma with respect to the local standard of rest (LSR). The Kolmogorov power
law is a satisfactory model for the electron density spectrum at scales between
20 megameters and 1 gigameter. We compare the observations with model
calculations from weak scintillation theory and the known transverse velocities
of the pulsar and the Earth. The simplest model is that the scattering is
uniformly distributed along the 310 pc line of sight (l=140 deg, b=32 deg) and
is stationary in the LSR. With the scattering measure as the only free
parameter, this model fits the data within the errors and a range of about
+/-10 km/s in velocity is also allowed.
  The integrated level of turbulence is low, being comparable to that found
toward PSR B0950+08, and suggests a region of low local turbulence over as much
as 90 deg. in longitude including the galactic anti-center. If, on the other
hand, the scattering occurs in a compact region, the observed time scales
require a specific velocity-distance relation. In particular, enhanced
scattering in a shell at the edge of the local bubble, proposed by Bhat et al.
(1998), near 72 pc toward the pulsar, must be moving at about ~ 17 km/s;
however, the low scattering measure argues against a shell of enhanced
scattering in this direction. The analysis also excludes scattering in the
termination shock of the solar wind or in a nebula associated with the pulsar.

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The categories of this paper are: plasm-ph
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The categories of this paper are: solv-int
9
The categories of this paper are: nlin
22
The categories of this paper are: chao-dyn
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The categories of this paper are: alg-geom
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The categories of this paper are: hep-ex
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The categories of this paper are: cs
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The categories of this paper are: mtrl-th
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The categories of this paper are: eess
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The categories of this paper are: physics
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The categories of this paper are: cmp-lg
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The categories of this paper are: q-fin
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The categories of this paper are: q-alg
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The categories of this paper are: hep-th
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The categories of this paper are: hep-ph
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The categories of this paper are: adap-org