Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Re-determining the Galactic spiral density wave parameters from data on
  masers with trigonometric parallaxes   The parameters of the Galactic spiral wave are re-determined using a modified
periodogram (spectral) analysis of the galactocentric radial velocities of 58
masers with known trigonometric parallaxes, proper motions, and line-of-site
velocities. The masers span a wide range of galactocentric distances,
$3<$R$<14$ kpc, which, combined with a large scatter of position angles
$\theta$ of these objects in the Galactic plane XY, required an accurate
account of logarithmic dependence of spiral-wave perturbations on both
galactocentric distance and position angle. A periodic signal was detected
corresponding to the spiral density wave with the wavelength $\lambda=2.4 \pm
0.4$ kpc, peak velocity of wave perturbations $f_R=7.5 \pm 1.5$ km s$^{-1}$,
the phase of the Sun in the density wave $\chi_\odot=-160 \pm 15^\circ$, and
the pitch angle of $-5.5 \pm 1^\circ$.

16
The categories of this paper are: stat
26
The categories of this paper are: bayes-an
1
The categories of this paper are: cs
32
The categories of this paper are: atom-ph
20
The categories of this paper are: acc-phys
4
The categories of this paper are: cond-mat
10
The categories of this paper are: q-bio
12
The categories of this paper are: nucl-th
28
The categories of this paper are: alg-geom
11
The categories of this paper are: hep-lat
34
The categories of this paper are: chem-ph
19
The categories of this paper are: eess
15
The categories of this paper are: nucl-ex
36
The categories of this paper are: cmp-lg
9
The categories of this paper are: nlin
27
The categories of this paper are: comp-gas