Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Measurements of the Diffuse Ultraviolet Background and the Terrestrial
  Airglow with the Space Telescope Imaging Spectrograph   Far-UV observations in and near the Hubble Deep Fields demonstrate that the
Space Telescope Imaging Spectrograph (STIS) can potentially obtain unique and
precise measurements of the diffuse far-ultraviolet background. Although STIS
is not the ideal instrument for such measurements, high-resolution images allow
Galactic and extragalactic objects to be masked to very faint magnitudes, thus
ensuring a measurement of the truly diffuse UV signal. The programs we have
analyzed were not designed for this scientific purpose, but would be sufficient
to obtain a very sensitive measurement if it were not for a weak but
larger-than-expected signal from airglow in the STIS 1450-1900 A bandpass. Our
analysis shows that STIS far-UV crystal quartz observations taken near the limb
during orbital day can detect a faint airglow signal, most likely from NI\1493,
that is comparable to the dark rate and inseparable from the far-UV background.
Discarding all but the night data from these datasets gives a diffuse
far-ultraviolet background measurement of 501 +/- 103 ph/cm2/sec/ster/A, along
a line of sight with very low Galactic neutral hydrogen column (N_HI = 1.5E20
cm-2) and extinction (E(B-V)=0.01 mag). This result is in good agreement with
earlier measurements of the far-UV background, and should not include any
significant contribution from airglow. We present our findings as a warning to
other groups who may use the STIS far-UV camera to observe faint extended
targets, and to demonstrate how this measurement may be properly obtained with
STIS.

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The categories of this paper are: chem-ph
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The categories of this paper are: stat
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The categories of this paper are: econ
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The categories of this paper are: hep-ph
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The categories of this paper are: funct-an
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The categories of this paper are: supr-con
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The categories of this paper are: acc-phys
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The categories of this paper are: eess
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The categories of this paper are: chao-dyn
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The categories of this paper are: quant-ph
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The categories of this paper are: hep-ex
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The categories of this paper are: dg-ga
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The categories of this paper are: nucl-ex
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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: physics