Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Recovery of Spectra of Phosphine in Venus' Clouds   We recover PH3 in the atmosphere of Venus in data taken with ALMA, using
three different calibration methods. The whole-planet signal is recovered with
5.4{\sigma} confidence using Venus bandpass self-calibration, and two simpler
approaches are shown to yield example 4.5-4.8{\sigma} detections of the
equatorial belt. Non-recovery by Villanueva et al. is attributable to (a)
including areas of the planet with high spectral-artefacts and (b) retaining
all antenna baselines which raises the noise by a factor ~2.5. We release a
data-processing script that enables our whole-planet result to be reproduced.
The JCMT detection of PH3 remains robust, with the alternative SO2 attribution
proposed by Villanueva et al. appearing inconsistent both in line-velocity and
with millimetre-wavelength SO2 monitoring. SO2 contamination of the ALMA
PH3-line is minimal. Net abundances for PH3, in the gas column above ~55 km,
are up to ~20 ppb planet-wide with JCMT, and ~7 ppb with ALMA (but with
signal-loss possible on scales approaching planetary size). Derived abundances
will differ if PH3 occupies restricted altitudes - molecules in the clouds will
contribute significantly less absorption at line-centre than equivalent numbers
of mesospheric molecules - but in the latter zone, PH3 lifetime is expected to
be short. Given we recover phosphine, we suggest possible solutions (requiring
substantial further testing): a small collisional broadening coefficient could
give narrow lines from lower altitude, or a high eddy diffusion coefficient
could allow molecules to survive longer at higher altitudes. Alternatively, PH3
could be actively produced by an unknown mechanism in the mesosphere, but this
would need to be in addition to cloud-level PH3 detected retrospectively by
Pioneer-Venus.

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The categories of this paper are: atom-ph
4
The categories of this paper are: cond-mat
2
The categories of this paper are: math
11
The categories of this paper are: hep-lat
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The categories of this paper are: chao-dyn
35
The categories of this paper are: mtrl-th
0
The categories of this paper are: hep-ph
9
The categories of this paper are: nlin
8
The categories of this paper are: hep-ex
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The categories of this paper are: supr-con
18
The categories of this paper are: econ
27
The categories of this paper are: comp-gas
13
The categories of this paper are: quant-ph
20
The categories of this paper are: acc-phys
23
The categories of this paper are: solv-int
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The categories of this paper are: nucl-ex