Metastable He transmission spectrum of HD 209458 b (left panel) and HAT-P-11 b (right panel) for uniformly sampled phases, transit impact parameter b = 0.499 and b = 0.132, respectively, and limb darkening based on the results of Knutson et al. (2007) and Sing (2010). The baseline (R_p/R_s)² was removed, as in actual ground-based observations. Phase 0.0 and 0.5 represent, respectively, the times of mid-transit and of first (or fourth) contact. The dashed red spectrum is the average of all phases between the first and fourth contact. The dot-dashed black curve is the average between second and third contact. These are forward models, and we are not yet attempting to fit them to observed signatures.