↩ 🔵 🔵 🔵 ❪✺❫ High-Energy Astrophysics Concepts ○ ❪✺₄❫ Astronomical Sets ○ ❪✺₄❫ Spectral Fitting Sets ○ ❪✺_ₛₛ❫ High-Energy Astrophysics Subsets ○ ❪◑❫ X-Ray Binaries ○ ❪◑❫ X-Ray States ○