Upper panel: STELLA/WiFSIP differential light curve of GJ1214b, gathered through a Bessel V filter during the 2012 and 2013 observing seasons. Unbinned points are shown in gray, daily averages are plotted with green points. Epochs corresponding to the two transits observed by LBC (T1 and T2) are marked with vertical lines. Middle panel: same as above, but through a Bessel I filter in 2012 (red points) and Bessel B in 2013 (blue points). Lower panels: GLS periodograms of the light curves, plotted with matching colors. The V periodogram has been evaluated on both the whole 2012/2013 data set (solid line) and only on the 2012 season (dashed line). The best-fit period, or the lower limit to it, is reported for each periodogram.