To obtain useful kinetic insights, we need to be able to set and stabilize T NP by controlling the heating laser power, meaning that we need real time T NP information. T NP is determined by fitting the NP thermal emission spectra, which are measured simultaneously with the F drive scans used to measure mass. As detailed elsewhere , emission from a ~100 μm volume at the trap center is collected over a ~0.7 steradian solid angle along the trap axis and collimated by a 5-lens system designed to reduce chromatic aberration. The beam is split by a 980 nm dichroic beamsplitter and injected into optical fibers that carry the light to a pair of spectrographs.