All Figures

Figure 1: Images of the 21 cm continuum, H I optical depth spectra and GBT recombination line spectra (where applicable) of the sources in our study. The left panel shows the continuum image with contours at -2 and 2 times the rms noise listed in Col. (9) of Table 1, and at factors of 2 thereafter. For sources with multiple velocity components, the component from which the H I spectrum is derived is marked with an ``X''. The right panel shows the line to continuum ratio, or . The source velocity, , and the tangent point velocity, , are indicated by short and long dashed lines, respectively. For sources with GBT recombination line data, the top right panel shows the H I spectrum, while the bottom right panel shows the recombination line spectrum in emission.

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In the text

	Figure 1: continued.
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In the text

	Figure 1: continued.
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In the text

	Figure 1: continued.
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In the text

	Figure 1: continued.
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In the text

	Figure 1: continued.
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In the text

	Figure 1: continued.
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In the text

	Figure 1: continued.
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In the text

	Figure 1: continued.
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In the text

	Figure 1: continued.
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In the text

	Figure 1: continued.
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In the text

	Figure 1: continued.
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In the text

Figure 2: Positions of the 6.7 GHz methanol masers and associated H II regions for which we have resolved the KDA. The left panel shows the distances using the conventional method labeled d in Table 1, while the right panel shows the distances calculated using the modified LSR velocity and rotation curve, labeled as d' in Table 1. The open and filled triangles show the distances with quality grades A and B respectively. The location of the Galactic Center is marked as ``GC''.

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In the text

Figure 3: H II regions with resolved KDA compiled from Kuchar & Bania (1994); Araya et al. (2002); Fish et al. (2003); Kolpak et al. (2003); Watson et al. (2003); Sewilo et al. (2004) and our study. Distances have been calculated using the C85 rotation curve. The left and right panels show the spiral arm loci of the NE2001 model of Cordes & Lazio (2002), and the Vallée (1995) model respectively. For clarity, no error bars are shown.

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In the text

Figure 4: H II regions with resolved KDA compiled from Kuchar & Bania (1994); Araya et al. (2002); Fish et al. (2003); Kolpak et al. (2003); Watson et al. (2003); Sewilo et al. (2004), and our study. Modified kinematic distances have been calculated using the procedure described in Sect. 4. The left and right panels show the spiral arm loci of the NE2001 model of Cordes & Lazio (2002), and the Vallée (1995) model respectively. For clarity, no error bars are shown.

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In the text