Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: A New Distance to The Antennae Galaxies (NGC 4038/39) Based on the Type
  Ia Supernova 2007sr   Traditionally, the distance to NGC 4038/39 has been derived from the systemic
recession velocity, yielding about 20 Mpc for H_0 = 72 km/s/Mpc. Recently, this
widely adopted distance has been challenged based on photometry of the presumed
tip of the red giant branch (TRGB), which seems to yield a shorter distance of
13.3+-1.0 Mpc and, with it, nearly 1 mag lower luminosities and smaller radii
for objects in this prototypical merger. Here we present a new distance
estimate based on observations of the Type Ia supernova (SN) 2007sr in the
southern tail, made at Las Campanas Observatory as part of the Carnegie
Supernova Project. The resulting distance of D(SN Ia) = 22.3+-2.8 Mpc [(m-M)_0
= 31.74+-0.27 mag] is in good agreement with a refined distance estimate based
on the recession velocity and the large-scale flow model developed by Tonry and
collaborators, D(flow) = 22.5+-2.8 Mpc. We point out three serious problems
that a short distance of 13.3 Mpc would entail, and trace the claimed short
distance to a likely misidentification of the TRGB. Reanalyzing Hubble Space
Telescope (HST) data in the Archive with an improved method, we find a TRGB
fainter by 0.9 mag and derive from it a preliminary new TRGB distance of
D(TRGB) = 20.0+-1.6 Mpc. Finally, assessing our three distance estimates we
recommend using a conservative, rounded value of D = 22+-3 Mpc as the best
currently available distance to The Antennae.

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The categories of this paper are: econ
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The categories of this paper are: acc-phys
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The categories of this paper are: supr-con
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The categories of this paper are: q-bio
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The categories of this paper are: nucl-ex
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The categories of this paper are: alg-geom
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The categories of this paper are: quant-ph
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The categories of this paper are: gr-qc
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The categories of this paper are: stat
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The categories of this paper are: physics
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The categories of this paper are: cs
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The categories of this paper are: bayes-an
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The categories of this paper are: hep-th
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The categories of this paper are: nlin
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The categories of this paper are: plasm-ph
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The categories of this paper are: hep-lat