Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Changes in night sky brightness after a countywide LED retrofit   The US National Park Service (NPS) Night Skies Program measured changes in
sky brightness resulting from a countywide lighting retrofit project. The
retrofit took place in Chelan County, a gateway community to North Cascades
National Park and Lake Chelan National Recreation Area in Washington State. The
county retrofitted all 3,693 county-owned high pressure sodium (HPS) street
lamps to full cutoff LEDs. This number is about 60% of the County's total
outdoor street and area lights. About 80% of the newly installed lights were
3000K in color temperature and 20% were 4000K. The 4000K LEDs were used to meet
Washington State Department of Transportation guidelines. To measure sky
brightness, we used the NPS night sky camera system before the retrofit started
in 2018 and after its completion in 2019. These images were photometrically
calibrated and mosaicked together to provide hemispherical images in V band.
For comparison with our ground-based measurement, we obtained the satellite
imagery taken by Visible Infrared Imaging Radiometer Suite (VIIRS) onboard the
Suomi National Polar-orbiting Partnership satellite. Our measurements show that
the post-retrofit skyglow became brighter and extended higher in the sky, but
upward radiance, as measured by the day-night band radiometer, decreased. These
divergent results are likely explained by a substantial increase in light
emitted at wavelengths shorter than 500 nm, and a relative decrease in zenith
light emission due to better shielded luminaires. These results also
demonstrate that earlier models relating VIIRS day-night band data to skyglow
will, at a minimum, require substantial revision to account for the different
characteristics of solid state luminaires.

14
The categories of this paper are: math-ph
8
The categories of this paper are: hep-ex
33
The categories of this paper are: plasm-ph
25
The categories of this paper are: patt-sol
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The categories of this paper are: quant-ph
28
The categories of this paper are: alg-geom
2
The categories of this paper are: math
27
The categories of this paper are: comp-gas
17
The categories of this paper are: q-fin
35
The categories of this paper are: mtrl-th
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The categories of this paper are: stat
22
The categories of this paper are: chao-dyn
31
The categories of this paper are: ao-sci
30
The categories of this paper are: q-alg
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The categories of this paper are: bayes-an
0
The categories of this paper are: hep-ph