Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: An Alignment System for Imaging Atmospheric Cherenkov Telescopes   The reflector used by an imaging atmospheric Cherenkov telescope (IACT)
consists of a tessellated array of mirrors mounted on a large frame. This
arrangement allows for a very large reflecting surface with sufficient optical
quality for the implementation of the IACT technique at a moderate price. The
main challenge presented by such a reflector is maintaining the optical
quality, which depends on the individual alignment of several hundred mirror
facets. We describe a method of measuring and correcting the alignment of the
mirror facets of the reflectors used by the VERITAS telescopes. This method
employs a CCD camera, placed at the focal point of the reflector, which
acquires a series of images of the reflector while the telescope performs a
raster scan about a star. Well-aligned facets appear bright when the telescope
points directly at the star while misaligned facets appear bright when the
angle between the telescope pointing direction and the star is twice the
misalignment angle of the mirror. Data from these scans can therefore be used
to produce a set of corrections which can be applied to the facets. In this
contribution we report on initial experience with an alignment system based on
this principle.

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The categories of this paper are: hep-ex
31
The categories of this paper are: ao-sci
35
The categories of this paper are: mtrl-th
37
The categories of this paper are: supr-con
24
The categories of this paper are: dg-ga
16
The categories of this paper are: stat
10
The categories of this paper are: q-bio
27
The categories of this paper are: comp-gas
30
The categories of this paper are: q-alg
12
The categories of this paper are: nucl-th
7
The categories of this paper are: hep-th
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The categories of this paper are: hep-ph
11
The categories of this paper are: hep-lat
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The categories of this paper are: cs
18
The categories of this paper are: econ
28
The categories of this paper are: alg-geom