Flux-density distributions at different observer-frame time points of the ɀ = 8 H band sample. These represent a 4.7 h ground-based reaction with current 6 m to 10 m class telescopes (top panel), a 12 h reaction with future 25 m to 40 m telescopes (middle panel), and a 3 days disruptive TOO reaction by JWST (bottom panel). With the arrows, we indicate the magnitude span over which each of the indicated telescope classes can acquire the required NIR spectrum (~ 2500 resolution) with a few hour integration time.