Upper panel: KELT-6 b transit light curve (2014 Apr. 11, IAC-80 telescope), and residuals from the best fit model (which is plotted with a solid blue line). The root mean square of the residuals is 0.9 mmag. Lower panel: O−C diagram including the highest-quality measurements from C014 plus one unpublished measurement from the KELT team (blue points on the left side) and from our IAC-80 observation (red point). The O−C diagram is folded on our newly determined ephemeris (solid red line), while the Co14 ephemeris is plotted with a dotted blue line.