Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Calibration of the Relationship between Precipitable Water Vapor and 225
  GHz Atmospheric Opacity via Optical Echelle Spectroscopy at Las Campanas
  Observatory   We report precipitable water vapor (PWV) measurements made at Las Campanas
Observatory using optical spectra of H2O lines obtained with the Magellan
echelle spectrograph, and calculated using a robust technique that is accurate
to 5-10%. Calibration of the relationship between our PWV measurements and
opacity values at 225 GHz was made possible by simultaneous tipping radiometer
observations. Based on this calibration, we present Las Campanas Observatory
winter-time precipitable water vapor statistics, measured using the tipping
radiometer, during a two month campaign. The median value of 2.8 +- 0.3 mm is
consistent with that measured at the nearby La Silla Observatory during the VLT
site survey. We conclude that, in the Southern hemisphere winter months, we can
expect good conditions for infrared observing (<~1.5 mm) approximately 10% of
the time at Las Campanas Observatory.

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The categories of this paper are: plasm-ph
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The categories of this paper are: q-fin
10
The categories of this paper are: q-bio
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The categories of this paper are: comp-gas
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The categories of this paper are: cmp-lg
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The categories of this paper are: adap-org
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The categories of this paper are: mtrl-th
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The categories of this paper are: hep-th
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The categories of this paper are: physics
0
The categories of this paper are: hep-ph
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The categories of this paper are: eess
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The categories of this paper are: cond-mat
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The categories of this paper are: bayes-an
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The categories of this paper are: hep-lat
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The categories of this paper are: supr-con
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The categories of this paper are: ao-sci