Modeled and observed mid-transit L-yα absorption of GJ 436b. We have used the in-transit data by Lavie et al. (2017) for out-of-transit and mid-transit observations. The core of the Ly-α line has been excluded, because it has been contaminated by geocoronal emission and thus cannot be observed. The contaminated region is marked by the dashed vertical lines and the blue shading. The green and orange lines show the mis-transit and out-of-transit observations (Lavie et al. 2017, Fig. 3). The blue line shows the modeled in-transit absorption.