Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: An Instrument For Investigation of the Cosmic Microwave Background
  Radiation at Intermediate Angular Scales   We describe an off-axis microwave telescope for observations of the
anisotropy in the cosmic microwave background (CMB) radiation on angular scales
between 0.5 deg and 3 deg. The receiver utilizes cryogenic
high-electron-mobility transistor (HEMT) amplifiers and detects the total power
in multiple 3 GHz wide channels. Both frequency and polarization information
are recorded allowing discrimination between CMB radiation and potential
foreground sources and allowing checks for systematic effects. The instrumental
radiometric offset is small (~1 mK). Data are taken by rapidly sampling while
sweeping the beam many beamwidths across the sky. After detection, a
spatio-temporal filter is formed in software which optimizes the sensitivity in
a multipole band in the presence of atmospheric fluctuations. Observations were
made from Saskatoon, Saskatchewan (SK), Canada during the winter of 1993 with
six channels between 27.6 and 34.0 GHz, in 1994 with twelve channels between
27.6 and 44.1 GHz, and in 1995 with six channels between 38.2 and 44.1 GHz. The
performance of the instrument and assessment of the atmospheric noise at this
site are discussed.

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The categories of this paper are: acc-phys
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The categories of this paper are: mtrl-th
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The categories of this paper are: q-alg
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The categories of this paper are: atom-ph
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The categories of this paper are: cs
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The categories of this paper are: adap-org
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The categories of this paper are: solv-int
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The categories of this paper are: cmp-lg
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The categories of this paper are: eess
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The categories of this paper are: econ
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The categories of this paper are: ao-sci
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The categories of this paper are: cond-mat
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The categories of this paper are: hep-ex
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The categories of this paper are: math
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The categories of this paper are: hep-ph
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The categories of this paper are: physics