Visiting astronomer, Cerro Tololo Inter-American Observatory, National Optical Astronomy Observatories, which are operated by the Association of Universities for Research in Astronomy, under contract with the National Science Foundation.

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Note that in old literature, this arm was sometimes called the "4-kpc expanding arm'' due to a distance to the GC of 10.0 kpc.

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... accuracy

Note that this argument cannot be applied to G10.0-0.3, simply because it is not an H II region.

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