Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: The Hubble Sphere Hydrogen Survey   An all sky redshift survey, using hydrogen 21 cm emission to locate galaxies,
can be used to track the wavelength of baryon acoustic oscillations imprints
from z ~ 1.5 to z = 0. This will allow precise determination of the evolution
of dark energy. A telescope made of fixed parabolic cylindrical reflectors
offers substantial benefit for such a redshift survey. Fixed cylinders can be
built for low cost, and long cylinders also allow low cost fast fourier
transform techniques to be used to define thousands of simultaneous beams. A
survey made with fixed reflectors naturally covers all of the sky available
from it's site with good uniformity, minimizing sample variance in the
measurement of the acoustic peak wavelength. Such a survey will produce about a
billion redshifts, nearly a thousand times the number available today. The
survey will provide a three dimensional mapping of a substantial fraction of
the Hubble Sphere.

36
The categories of this paper are: cmp-lg
3
The categories of this paper are: physics
2
The categories of this paper are: math
18
The categories of this paper are: econ
27
The categories of this paper are: comp-gas
16
The categories of this paper are: stat
29
The categories of this paper are: funct-an
12
The categories of this paper are: nucl-th
21
The categories of this paper are: adap-org
37
The categories of this paper are: supr-con
30
The categories of this paper are: q-alg
1
The categories of this paper are: cs
7
The categories of this paper are: hep-th
17
The categories of this paper are: q-fin
9
The categories of this paper are: nlin
4
The categories of this paper are: cond-mat