A rotation curve for the Galaxy within the solar circle is found using data from the fourth Galactic quadrant. The observations are consistent with a picture in which the Galaxy rotates with a circular velocity of 209 + or - 2 km/s between Galactocentric distances of 0.24 and 1.0 solar radius. Clouds associated with a part of the Carina spiral arm exhibit an average rotation velocity 12 km/s higher than expected, implying an apparent anomalous motion. An excess in velocity of about the same magnitude observed at the tangent direction of the Centaurus arm is attributed to streaming and internal motions of large molecular complexes. Similar phenomena found in the Sagittarius and Scutum arms by northern observers strongly support the hypothesis that Carina is the continuation of the Sagittarius arm and Centaurus is that of the Scutum arm.
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Álvarez et al. (1990) studied this question.