GaussPy+: A fully automated Gaussian decomposition package for emission
  line spectra
  Our understanding of the dynamics of the interstellar medium is informed by
the study of the detailed velocity structure of emission line observations. One
approach to study the velocity structure is to decompose the spectra into
individual velocity components; this leads to a description of the dataset that
is significantly reduced in complexity. However, this decomposition requires
full automation lest it becomes prohibitive for large datasets, such as
Galactic plane surveys. We developed GaussPy+, a fully automated Gaussian
decomposition package that can be applied to emission line datasets, especially
large surveys of HI and isotopologues of CO. We built our package upon the
existing GaussPy algorithm and significantly improved its performance for noisy
data. New functionalities of GaussPy+ include: i) automated preparatory steps,
such as an accurate noise estimation, which can also be used as standalone
applications; ii) an improved fitting routine; iii) an automated spatial
refitting routine that can add spatial coherence to the decomposition results
by refitting spectra based on neighbouring fit solutions. We thoroughly tested
the performance of GaussPy+ on synthetic spectra and a test field from the
Galactic Ring Survey. We found that GaussPy+ can deal with cases of complex
emission and even low to moderate signal-to-noise values.
