Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: The Megamaser Cosmology Project. XI. A geometric distance to CGCG
  074-064   As part of the survey component of the Megamaser Cosmology Project, we have
discovered a disk megamaser system in the galaxy CGCG 074-064. Using the GBT
and the VLA, we have obtained spectral monitoring observations of this maser
system at a monthly cadence over the course of two years. We find that the
systemic maser features display line-of-sight accelerations of ~4.4 km s$^{-1}$
yr$^{-1}$ that are nearly constant with velocity, while the high-velocity maser
features show accelerations that are consistent with zero. We have also used
the HSA to make a high-sensitivity VLBI map of the maser system in CGCG
074-064, which reveals that the masers reside in a thin, edge-on disk with a
diameter of ~1.5 mas (0.6 pc). Fitting a three-dimensional warped disk model to
the data, we measure a black hole mass of $2.42^{+0.22}_{-0.20} \times 10^7$
M$_{\odot}$ and a geometric distance to the system of $87.6^{+7.9}_{-7.2}$ Mpc.
Assuming a CMB-frame recession velocity of $7308 \pm 150$ km s$^{-1}$, we
constrain the Hubble constant to $H_0 = 81.0^{+7.4}_{-6.9}$ (stat.) $\pm 1.4$
(sys.) km s$^{-1}$ Mpc$^{-1}$.

37
The categories of this paper are: supr-con
9
The categories of this paper are: nlin
8
The categories of this paper are: hep-ex
11
The categories of this paper are: hep-lat
32
The categories of this paper are: atom-ph
27
The categories of this paper are: comp-gas
15
The categories of this paper are: nucl-ex
22
The categories of this paper are: chao-dyn
20
The categories of this paper are: acc-phys
5
The categories of this paper are: gr-qc
28
The categories of this paper are: alg-geom
35
The categories of this paper are: mtrl-th
1
The categories of this paper are: cs
31
The categories of this paper are: ao-sci
3
The categories of this paper are: physics
17
The categories of this paper are: q-fin