HATS-77 is an orange K-type dwarf (about 0.66 solar masses, 4,071 K, 0.64 solar radii), 436 light-years from Earth. HATS-77 b is a 1.37-Jupiter-mass companion, with an orbital period of 3.1 days, at 0.036 AU from its star, and an equilibrium temperature near 828 K, discovered in 2021 via transit. The inner world is a hot Jupiter — a gas giant hugging its star at a fraction of Mercury's distance — a class that forced astronomers to rethink how giant planets form and migrate inward.