Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: An Improved Photometric Calibration of the Sloan Digital Sky Survey
  Imaging Data   We present an algorithm to photometrically calibrate wide field optical
imaging surveys, that simultaneously solves for the calibration parameters and
relative stellar fluxes using overlapping observations. The algorithm decouples
the problem of "relative" calibrations, from that of "absolute" calibrations;
the absolute calibration is reduced to determining a few numbers for the entire
survey. We pay special attention to the spatial structure of the calibration
errors, allowing one to isolate particular error modes in downstream analyses.
Applying this to the Sloan Digital Sky Survey imaging data, we achieve ~1%
relative calibration errors across 8500 sq.deg. in griz; the errors are ~2% for
the u band. These errors are dominated by unmodelled atmospheric variations at
Apache Point Observatory. These calibrations, dubbed "ubercalibration", are now
public with SDSS Data Release 6, and will be a part of subsequent SDSS data
releases.

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The categories of this paper are: chao-dyn
32
The categories of this paper are: atom-ph
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The categories of this paper are: acc-phys
9
The categories of this paper are: nlin
8
The categories of this paper are: hep-ex
15
The categories of this paper are: nucl-ex
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The categories of this paper are: ao-sci
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The categories of this paper are: alg-geom
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The categories of this paper are: eess
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The categories of this paper are: quant-ph
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The categories of this paper are: q-bio
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The categories of this paper are: cmp-lg
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The categories of this paper are: cond-mat
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The categories of this paper are: comp-gas
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The categories of this paper are: adap-org
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The categories of this paper are: chem-ph