LESSPayne performs semi-automatic analysis for echelle spectra of stars. It uses a neural network emulator to do a full spectrum fit to estimate stellar parameters and performs automatic continuum and equivalent width fits normalization with theoretical masks. The code uses MOOG (ascl:1202.009) for spectrum synthesis fitting, ATLAS model atmosphere interpolation, and equivalent width abundance determination. LESSPayne can also perform automatic abundance uncertainty analysis with error propagation and summary tables, and should be viewed as providing a high-quality initialization for an smhr file that reduces the time for a standard analysis.

The Payne precisely and simultaneously determines numerous stellar labels from observed spectra based on fitting physical spectral models. It fits all all labels (stellar parameters and element abundances) simultaneously, and uses spectral models where the atmosphere structure and the radiative transport are consistently calculated to reflect the stellar labels. The Payne leads to both precise and accurate estimates of stellar labels, based on physical models and without re-calibration.