Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Kinematics of two dwarf galaxies in the NGC 6946 group   We present high velocity resolution (~ 1.6 km/s) Giant Meterwave Radio
Telescope (GMRT) HI 21 cm synthesis images of the dwarf galaxies KK98 250 and
KK98 251, as well as optical broad band images of KK98 250. We find that,
despite being faint (M_B <-14), both galaxies have regular velocity fields. In
both cases the velocity fields are consistent with rigid body rotation. We
derive rotation curves for the galaxies and fit mass models to them. For both
galaxies, we find acceptable fits using isothermal halos while NFW halos
provide a poor fit. Finally, we compile from literature a sample of galaxies
with HI synthesis observations and I band magnitudes. From this sample we find,
in agreement with earlier studies (which used single dish HI data), that dwarf
galaxies tend to lie below the I band Tully-Fisher relation defined by brighter
galaxies.

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The categories of this paper are: math
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The categories of this paper are: dg-ga
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The categories of this paper are: bayes-an
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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: cs
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The categories of this paper are: hep-ph
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The categories of this paper are: solv-int
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The categories of this paper are: nucl-th
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The categories of this paper are: math-ph
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The categories of this paper are: nucl-ex
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The categories of this paper are: comp-gas
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The categories of this paper are: funct-an
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The categories of this paper are: eess
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The categories of this paper are: chem-ph
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The categories of this paper are: cmp-lg