Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: The Vanishing & Appearing Sources during a Century of Observations
  project: I. USNO objects missing in modern sky surveys and follow-up
  observations of a "missing star"   In this paper we report the current status of a new research program. The
primary goal of the "Vanishing & Appearing Sources during a Century of
Observations" (VASCO) project is to search for vanishing and appearing sources
using existing survey data to find examples of exceptional astrophysical
transients. The implications of finding such objects extend from traditional
astrophysics fields to the more exotic searches for evidence of technologically
advanced civilizations. In this first paper we present new, deeper observations
of the tentative candidate discovered by Villarroel et al. (2016). We then
perform the first searches for vanishing objects throughout the sky by
comparing 600 million objects from the US Naval Observatory Catalogue (USNO)
B1.0 down to a limiting magnitude of $\sim 20 - 21$ with the recent Pan-STARRS
Data Release-1 (DR1) with a limiting magnitude of $\sim$ 23.4. We find about
150,000 preliminary candidates that do not have any Pan-STARRS counterpart
within a 30 arcsec radius. We show that these objects are redder and have
larger proper motions than typical USNO objects. We visually examine the images
for a subset of about 24,000 candidates, superseding the 2016 study with a
sample ten times larger. We find about $\sim$ 100 point sources visible in only
one epoch in the red band of the USNO which may be of interest in searches for
strong M dwarf flares, high-redshift supernovae or other catagories of
unidentified red transients.

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The categories of this paper are: mtrl-th
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The categories of this paper are: patt-sol
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The categories of this paper are: nucl-ex
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The categories of this paper are: quant-ph
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The categories of this paper are: q-fin
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The categories of this paper are: stat
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The categories of this paper are: bayes-an
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The categories of this paper are: acc-phys
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The categories of this paper are: comp-gas
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The categories of this paper are: q-alg
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The categories of this paper are: nucl-th
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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: supr-con
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The categories of this paper are: cmp-lg
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The categories of this paper are: plasm-ph