Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Transparency of 2 {\mu}m window of Titan's atmosphere   Titan's atmosphere is optically thick and hides the surface and the lower
layers from the view at almost all wavelengths. However, because gaseous
absorptions are spectrally selective, some narrow spectral intervals are
relatively transparent and allow to probe the surface. To use these intervals
(called windows) a good knowledge of atmospheric absorption is necessary. Once
gas spectroscopic linelists are well established, the absorption inside windows
depends on the way the far wings of the methane absorption lines are cut-off.
We know that the intensity in all the windows can be explained with the same
cut-off parameters, except for the window at 2 {\mu}m. This discrepancy is
generally treated with a workaround which consists in using a different cut-off
description for this specific window. This window is relatively transparent and
surface may have specific spectral signatures that could be detected. Thus, a
good knowledge of atmosphere opacities is essential and our scope is to better
understand what causes the difference between the 2 {\mu}m window and the other
windows. In this work, we used scattered light at the limb and transmissions in
occultation observed with VIMS (Visual Infrared Mapping Spectrometer) onboard
Cassini, around the 2 {\mu}m window. Data shows an absorption feature that
participates to the shape of this window. Our atmospheric model fits well the
VIMS data at 2 {\mu}m with the same cut-off than for the other windows,
provided an additional absorption is introduced in the middle of the window
around ~2.065 {\mu}m. It explains well the discrepancy between the cut-off used
at 2 {\mu}m, and we show that a gas with a fairly constant mixing ratio,
possibly ethane, may be the cause of this absorption. Finally, we studied the
impact of this absorption on the retrieval of the surface reflectivity and
found that it is significant.

21
The categories of this paper are: adap-org
15
The categories of this paper are: nucl-ex
7
The categories of this paper are: hep-th
5
The categories of this paper are: gr-qc
10
The categories of this paper are: q-bio
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The categories of this paper are: solv-int
32
The categories of this paper are: atom-ph
20
The categories of this paper are: acc-phys
31
The categories of this paper are: ao-sci
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The categories of this paper are: dg-ga
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The categories of this paper are: stat
28
The categories of this paper are: alg-geom
9
The categories of this paper are: nlin
12
The categories of this paper are: nucl-th
29
The categories of this paper are: funct-an
1
The categories of this paper are: cs