Constant curve25519_dalek::constants::ED25519_BASEPOINT

pub const ED25519_BASEPOINT: ExtendedPoint = ExtendedPoint{X:
                  FieldElement([-14297830, -7645148, 16144683, -16471763,
                                27570974, -2696100, -26142465, 8378389,
                                20764389, 8758491]),
              Y:
                  FieldElement([-26843541, -6710886, 13421773, -13421773,
                                26843546, 6710886, -13421773, 13421773,
                                -26843546, -6710886]),
              Z: FieldElement([1, 0, 0, 0, 0, 0, 0, 0, 0, 0]),
              T:
                  FieldElement([28827062, -6116119, -27349572, 244363,
                                8635006, 11264893, 19351346, 13413597,
                                16611511, -6414980]),}

Basepoint has y = 4/5.