Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: The Orbit and Transit Prospects for $\beta$ Pictoris b constrained with
  One Milliarcsecond Astrometry   A principal scientific goal of the Gemini Planet Imager (GPI) is obtaining
milliarcsecond astrometry to constrain exoplanet orbits. However, astrometry of
directly imaged exoplanets is subject to biases, systematic errors, and speckle
noise. Here we describe an analytical procedure to forward model the signal of
an exoplanet that accounts for both the observing strategy (angular and
spectral differential imaging) and the data reduction method (Karhunen-Lo\`eve
Image Projection algorithm). We use this forward model to measure the position
of an exoplanet in a Bayesian framework employing Gaussian processes and Markov
chain Monte Carlo (MCMC) to account for correlated noise. In the case of GPI
data on $\beta$ Pic b, this technique, which we call Bayesian KLIP-FM
Astrometry (BKA), outperforms previous techniques and yields 1$\sigma$-errors
at or below the one milliarcsecond level. We validate BKA by fitting a
Keplerian orbit to twelve GPI observations along with previous astrometry from
other instruments. The statistical properties of the residuals confirm that BKA
is accurate and correctly estimates astrometric errors. Our constraints on the
orbit of $\beta$ Pic b firmly rule out the possibility of a transit of the
planet at 10-$\sigma$ significance. However, we confirm that the Hill sphere of
$\beta$ Pic b will transit, giving us a rare chance to probe the
circumplanetary environment of a young, evolving exoplanet. We provide an
ephemeris for photometric monitoring of the Hill sphere transit event, which
will begin at the start of April in 2017 and finish at the end of January in
2018.

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The categories of this paper are: ao-sci
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The categories of this paper are: acc-phys
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The categories of this paper are: math-ph
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The categories of this paper are: solv-int
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The categories of this paper are: eess
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The categories of this paper are: q-alg
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The categories of this paper are: nucl-th
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The categories of this paper are: comp-gas
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The categories of this paper are: nucl-ex
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The categories of this paper are: bayes-an
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The categories of this paper are: dg-ga
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The categories of this paper are: atom-ph
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The categories of this paper are: quant-ph
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The categories of this paper are: nlin
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The categories of this paper are: hep-th
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The categories of this paper are: chem-ph