MoonIndex, an Open-Source Tool to Generate Spectral Indexes for the Moon from M3 Data

Spectral indexes are tools widely used to analyze the composition of the lunar surface. Many indexes have been formulated over the years, but there is no unified database for them. In this work we describe an Open-Source Python package called MoonIndex, that recreates thirty-nine indexes compiled from the literature and derived from several instruments, using data from the Moon Mineralogy Mapper (M3). The processing started with the filtration of the data cubes to reduce the noise, the continuum of the spectrum was then removed using the convex hull and linear-fit methods. Later, the indexes were calculated, following as possible the original formulations. The results on spectral indexes calculated on the original spectra were similar to those already published. Conversely, the results obtained for spectral indexes calculated after the continual removal were not always coherent, some indexes, like the band depth, are especially sensitive to the removal method, as well as the derived band areas and asymmetries. We also recreated RGB composite maps, our results highlight the compositional patterns is a similar way as the ones in the literature, even if the color ramps can differ. The products of MoonIndex are open, ready for interpretation, versatile, consistent, and cross-comparable.