The JWST integration time (Δt) necessary to achieve an S/N of ∼5 using eclipse (i.e., thermal emission) spectroscopy for an Earth-analog around a brown dwarf plotted as a function of the brown dwarf’s age. We have specified d = 10 pc, λ = 10 μm, and ζ = 0.5 in (20). The dotted, unbroken, and dashed black curves depict Δt for brown dwarfs whose masses are 10 M_J, 40 M_J, and 70 M_J, respectively. The horizontal red line demarcates the desirable region where the integration time is <10 hr.