deletions | additions       diff --git a/sectionMethdology_To.tex b/sectionMethdology_To.tex  index b9460c8..fc66f96 100644  --- a/sectionMethdology_To.tex  +++ b/sectionMethdology_To.tex 
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For features that appear associated with spiral arms on the 2-D plane of the sky, radial velocity data is needed to establish whether 3-D association with a spiral feature is likely. The filament must have similar line-of-sight velocities along its length to ensure its contiguity. Moreover, the measured radial velocities should be very close to those predicted by the Milky Way's rotation curve for arms at a known distance. To investigate the velocity structure of these fifteen filaments, we employ radial velocity data from five separate radio surveys: HOPS \citep{Purcell_2012,Walsh_2011}, MALT90 \citep{Foster_2011,Jackson_2013}, BGPS spectral line follow-up \cite{Schlingman_2011,Shirley_2013, Ellsworth_Bowers_2013}, GRS \citep{Jackson_2006} and ThrUMMS \cite{Barnes_2011}. The HOPS, MALT90, and BGPS surveys are all geared towards probing dense regions hosting the early stages of high mass star formation. We utilize $\textrm{NH}_3$ emission from HOPS, $\mathrm{N_2H^{+}}$ from MALT90, and $\textrm{HCO}^{+}$ from BGPS. All three of these thermal emission lines trace dense molecular gas ($\approx10^{4}\textrm{ cm}^{-3}$) and are often found in dense, cool clouds with temperatures less than 100 K \citep{Purcell_2012, Shirley_2013}. As infrared dark clouds tend to harbor cool, high density clumps of gas which fuel the formation of massive stars, all three of these data sets contain spectra for hundreds of regions within the longitude range of the potential Galactic bones.   We investigate the velocity structure of our filaments in two ways: first, whenever possible, we establish the velocity coherence of our candidates by performing a slice extraction along each filamentary extinction feature in \href{http://www.glueviz.org/en/stable/index.html}{Glue}, a visualization tool that facilitates the linking of data sets. We link spectral \textit{p-p-v} cubes from the GRS and ThrUMMS survey with GLIMPSE-Spitzer mid-infrared images and obtain velocity as a function of position along a path that traces the entire extinction feature. The results of the slice extraction along the path of one of our strongest bone candidates is shown in figure \ref{fig:filament5_slice}. We are able to establish velocity coherence for all candidates lying within the coverage range of the GRS survey ($ 18^\circ > l < 56^\circ$) and the ThrUMMS survey ($ 350^\circ > l < 358^\circ$).  In cases where HOPS, MALT90, and BGPS catalog data are not available along the extinction feature, we also extract spectra from GRS (high resolution $^{13}$CO (1-0) data) and MALT90 \textit{p-p-v} cubes using the spectrum extracter tool in \href{http://www.glueviz.org/en/stable/index.html}{Glue}. Glue is a visualization tool that facilitates the linking of various data sets. We link spectral \textit{p-p-v} cubes from the GRS survey with GLIMPSE-Spitzer mid-infrared images and extract velocities along different regions of the extinction feature; a demonstration of the procedure used to extract velocities in Glue is shown in the appendix. In order to ensure that that GRS velocities are consistent across the filament, we also use the slice extraction tool in Glue to obtain velocity as a function of position along a path that traces the entire extinction feature.The results of the slice extraction along the path of one of our strongest bone candidates, filament 5, is shown in figure \ref{fig:filament5_slice}. Since CO traces lower density gas ($\approx10^2 \textrm{ cm}^{-3}$) and $\mathrm{N_2H+}$, $\textrm{HCO}^+$, and $\textrm{NH}_3$ trace high density gas ($\approx10^4 \textrm{ cm}^{-3}$), the dense gas sources provide much stronger evidence for the velocity of cold, dense, filamentary IRDCs. However, where dense gas sources are not available, the complete and unbiased high resolution GRS survey, although less desirable, allows us to roughly gauge the velocity along entire lengths of filaments. In filaments composed entirely of GRS spectra, we also take HOPS spectra over the entire filament using Glue and confirm that this HOPS-determined velocity agreed with GRS-determined average velocity to within 5 km/s.