Top panel: Kiel diagram of high signal-to-noise stars from the H3 survey, color-coded by the relative age uncertainty. Main-sequence turn-off stars, delimited by red horizontal lines (﹩3.8\lt \mathrm{log}\,g\lt 4.3﹩), have precisely determined ages (the median uncertainty is 10%). Bottom panel: cylindrical Galactocentric coordinates of the main-sequence turn-off stars we studied in this work. Our sample is radially confined to the solar circle (6 ≲ R/﹩\mathrm{kpc}﹩ ≲ 10), and vertically extends between ﹩1\lesssim | Z| /\mathrm{kpc}\lesssim 4﹩, beyond the scale heights of the thin and thick disks (dashed and dotted horizontal lines, respectively).