Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: The Hubble Deep Field: Observations, Data Reduction, and Galaxy
  Photometry   The Hubble Deep Field (HDF) is a Director's Discretionary program on HST in
Cycle 5 to image an undistinguished field at high Galactic latitude in four
passbands as deeply as reasonably possible. These images provide the most
detailed view to date of distant field galaxies and are likely to be important
for a wide range of studies in galaxy evolution and cosmology. In order to
optimize observing in the time available, a field in the northern continuous
viewing zone was selected and images were taken for ten consecutive days, or
approximately 150 orbits. Shorter 1-2 orbit images were obtained of the fields
immediately adjacent to the primary HDF in order to facilitate spectroscopic
follow-up by ground-based telescopes. The observations were made from 18 to 30
December 1995, and both raw and reduced data have been put in the public domain
as a community service.
  We present a summary of the criteria for selecting the field, the rationale
behind the filter selection and observing times in each band, and the
strategies for planning the observations to maximize the exposure time while
avoiding earth-scattered light. Data reduction procedures are outlined, and
images of the combined frames in each band are presented. Objects detected in
these images are listed in a catalog with their basic photometric parameters.

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The categories of this paper are: math
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The categories of this paper are: chem-ph
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The categories of this paper are: hep-ph
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The categories of this paper are: cs
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The categories of this paper are: patt-sol
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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: cond-mat
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The categories of this paper are: mtrl-th
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The categories of this paper are: dg-ga
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The categories of this paper are: adap-org
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The categories of this paper are: hep-lat
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The categories of this paper are: solv-int
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The categories of this paper are: plasm-ph
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The categories of this paper are: chao-dyn
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The categories of this paper are: atom-ph