ABSTRACT
We summarize the suite of modern gamma-ray observatories like the Fermi Large Area Telescope, the High Energy Stereoscopic System, and the High Altitude Water Cherenkov observatory. This discussion is focused on experimental design and instrument performance. We describe what factors determine things like a point spread function and energy resolution and compare the performance of each observatory. This suite of gamma-ray observatories that all work together to enable the most detailed study of cosmic gamma rays in history.
