↩ 🔵 🔵 🔵 ❪✺❫ High-Energy Astrophysics Concepts ○ ❪✺_❫ Astronomical Subs ○ ❪✺_❫ HEASoft Subs ○ ❪✺_❫ Spectral Fitting Subs ○ ❪✺_ₛₛ❫ High-Energy Astrophysics Subsets ○ Continuous Clocking Mode ○˒ Photon Counting Mode ○˒ Windowed Timing Mode ○˒