Determination of the extinction law. All the panels and inset share the same color-coding and line style. The best fit for the RC (computed in Sect. 3.1) is shown with a dashed white line; the derived extinction law is shown as a dotted gold line; the color at which RC stars change the direction of rotation with respect to Sgr A* is represented with a solid red line and a shadowed gray area; and the K magnitude at which the maximum of the RC is at the color of transition in kinematics is shown with a solid purple line. A: zoom on the region near the RC anchor. The crosses show the positions of the RC in low-extinction windows without uncertainties. The gold star with black edges represents the anchor RC position, which is the average of the RC in the windows. B: color–magnitude diagram showing the RC selection colored by density. The gray dots represent all the stars not included in the RC selection. C: color–magnitude diagram of NBF stars cross-matched with VVV stars. Each bin is colored by the mean PM along the Galactic latitude with respect to Sgr A*. The contours show the density of RC selection stars. D: K LF within the 0.1 mag around (H-K)^KC0. The orange histogram represents the LF, and the solid black line represents the KDE fit. E: longitudinal proper motions with respect to the proper motion of Sgr A* as a function of the observed color. The gray background represents the density of stars in this space. A logarithmic stretch was applied for better visualization. The black dots show the median of each 0.1 mag in color. The solid black line represents the best fit for the medians. The horizontal dashed black line shows where the proper motion with respect to the Sgr A* changes its rotation direction.