MSG: A software package for interpolating stellar spectra in pre-calculated grids.

While the spectrum of the light emitted by a star can be calculated by simulating the flow of radiation through each layer of the star's atmosphere, this process is computationally expensive. Therefore, it is often far more efficient to pre-calculate spectra over a grid of photospheric parameters, and then interpolate within this grid. MSG (short for Multidimensional Spectral Grids) is a software package that implements this interpolation capability.