The modular bootstrap program for two-dimensional conformal field theories could be seen as a systematic exploration of the physical consequences of consistency conditions at the elliptic points and at the cusp of their torus partition function. The study at τ = i, the elliptic point stabilized by the modular inversion S, was initiated by Hellerman, who found a general upper bound for the most relevant scaling dimension ∆. Likewise, analyticity at τ = i∞, the cusp stabilized by the modular translation T , yields an upper bound on the twist gap. Here we study consistency conditions at τ = exp[2iπ/3], the elliptic point stabilized by S T . We find a much stronger upper bound in the large-c limit, namely ∆ < c−1 12 + 0.092, which is very close to the minimal mass threshold of the BTZ black holes in the gravity dual of AdS3/CF T2 correspondence.