Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: A search for 4750- and 4765-MHz OH masers in Southern Star Forming
  Regions   We have used the Australia Telescope Compact Array (ATCA) to make a sensitive
(5-$\sigma$ $\simeq$ 100 mJy) search for maser emission from the 4765-MHz
$^2\Pi_{1/2}$ F=1$\to$0 transition of OH. Fifty five star formation regions
were searched and maser emission with a peak flux density in excess of 100 mJy
was detected toward fourteen sites, with ten of these being new discoveries. In
addition we observed the 4750-MHz $^2\Pi_{1/2}$ F=1$\to$1 transition towards a
sample of star formation regions known to contain 1720-MHz OH masers, detecting
marginal maser emission from G348.550-0.979. If confirmed this would be only
the second maser discovered from this transition. The occurrence of 4765-MHz OH
maser emission accompanying 1720-MHz OH masers in a small number of well
studied star formation regions has lead to a general perception in the
literature that the two transitions favour similar physical conditions. Our
search has found that the presence of the excited-state 6035-MHz OH transition
is a much better predictor of 4765-MHz OH maser emission from the same region
than is 1720-MHz OH maser emission. Combining our results with those of
previous high resolution observations of other OH transitions we have examined
the published theoretical models of OH masers and find that none of them
predict any conditions in which the 1665-, 6035- and 4765-MHz transitions are
simultaneously inverted.
  Erratum abstract:
  Dodson & Ellingsen (2002) included several observations with significant
pointing errors, invalidating the upper limits found in these directions. These
have now been reobserved or recalculated. A new table of upper limits has been
generated, and two more masers that would have been seen have been found.

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The categories of this paper are: math-ph
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The categories of this paper are: patt-sol
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The categories of this paper are: nucl-th
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The categories of this paper are: q-alg
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The categories of this paper are: eess
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The categories of this paper are: supr-con
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The categories of this paper are: solv-int
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The categories of this paper are: adap-org
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The categories of this paper are: mtrl-th
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The categories of this paper are: gr-qc
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The categories of this paper are: cs
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The categories of this paper are: ao-sci
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The categories of this paper are: hep-th
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The categories of this paper are: alg-geom
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The categories of this paper are: econ
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The categories of this paper are: quant-ph