Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: An Upper Limit on the Albedo of HD 209458b: Direct Imaging Photometry
  with the MOST Satellite   We present space-based photometry of the transiting exoplanetary system HD
209458 obtained with the MOST (Microvariablity and Oscillations of STars)
satellite, spanning 14 days and covering 4 transits and 4 secondary eclipses.
The HD 209458 photometry was obtained in MOST's lower-precision Direct Imaging
mode, which is used for targets in the brightness range $6.5 < V < 13$. We
describe the photometric reduction techniques for this mode of observing, in
particular the corrections for stray Earthshine. We do not detect the secondary
eclipse in the MOST data, to a limit in depth of 0.053 mmag (1 \sigma). We set
a 1 \sigma upper limit on the planet-star flux ratio of 4.88 x 10^-5
corresponding to a geometric albedo upper limit in the MOST bandpass (400 to
700 nm) of 0.25. The corresponding numbers at the 3 \sigma level are 1.34 x
10^-4 and 0.68 respectively. HD 209458b is half as bright as Jupiter in the
MOST bandpass. This low geometric albedo value is an important constraint for
theoretical models of the HD209458b atmosphere, in particular ruling out the
presence of reflective clouds. A second MOST campaign on HD 209458 is expected
to be sensitive to an exoplanet albedo as low as 0.13 (1 sigma), if the star
does not become more intrinsically variable in the meantime.

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The categories of this paper are: bayes-an
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The categories of this paper are: cmp-lg
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The categories of this paper are: hep-th
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The categories of this paper are: cs
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The categories of this paper are: math
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The categories of this paper are: mtrl-th
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The categories of this paper are: nucl-th
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The categories of this paper are: nlin
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The categories of this paper are: quant-ph
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The categories of this paper are: q-fin
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The categories of this paper are: q-bio
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The categories of this paper are: patt-sol
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The categories of this paper are: solv-int
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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: funct-an