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We compare distance resolved, absolute proper motions in the Milky Waybar/bulge region to a grid of made-to-measure dynamical models with welldefined pattern speeds. The data are obtained by combining the relative VVVInfrared Astrometric Catalog v1 proper motions with the Gaia DR2 absolutereference frame. We undertake a comprehensive analysis of the various errors inour comparison, from both the data and the models, and allow for additional,unknown, contributions by using an outlier-tolerant likelihood function toevaluate the best fitting model. We quantify systematic effects such as theregion of data included in the comparison, the possible overlap from spiralarms, and the choice of synthetic luminosity function and bar angle used topredict the data from the models. Resulting variations in the best-fitparameters are included in their final errors. We thus measure the bar patternspeed to be ${\Omega}_b=33.29\pm1.81 \mathrm{km \, s^{-1} \, kpc^{-1}}$ and theazimuthal solar velocity to be $V_{\phi,\,\odot} = 251.31 \pm 1.95 \mathrm{km\, s^{-1}}$. These values, when combined with recent measurements of theGalactic rotation curve, yield the distance of corotation, 6.5 < $R_{CR}$ [kpc]< 7.5, the outer Lindblad resonance (OLR), 10.7 < $R_{OLR}$ [kpc] < 12.4, andthe higher order, m = 4, OLR, 8.7 < $R_{{OLR}_4}$ [kpc] < 10.0. The measuredpattern speed provides strong evidence for the "long-slow" bar scenario.

The Pattern Speed of the Milky Way Bar/Bulge from VIRAC & Gaia