2017ApJS..232...22D

As part of an extensive data mining effort, we have compiled a database of 162 Galactic rotation speed measurements at R₀ (the solar Galactocentric distance), Θ₀. Published between 1927 and 2017 June, this represents the most comprehensive set of Θ₀ values since the 1985 meta-analysis that led to the last revision of the International Astronomical Union's recommended Galactic rotation constants. Although we do not find any compelling evidence for the presence of "publication bias" in recent decades, we find clear differences among the Θ₀ values and the Θ₀/R₀ ratios resulting from the use of different tracer populations. Specifically, young tracers (including OB and supergiant stars, masers, Cepheid variables, H II regions, and young open clusters), as well as kinematic measurements of Sgr A* near the Galactic Center, imply a significantly larger Galactic rotation speed at the solar circle and a higher Θ₀/R₀ ratio (i.e., Θ₀=247±3 km s^–1 and Θ₀/R₀=29.81±0.32 km s^–1 kpc^–1; statistical uncertainties only) than any of the tracers dominating the Galaxy's mass budget (i.e., field stars and the H I/CO distributions). Using the latter to be most representative of the bulk of the Galaxy's matter distribution, we arrive at an updated set of Galactic rotation constants,