  pyspeckit is a toolkit and library for spectroscopic analysis in Python. We
describe the pyspeckit package and highlight some of its capabilities, such as
interactively fitting a model to data, akin to the historically widely-used
splot function in IRAF. pyspeckit employs the Levenberg-Marquardt optimization
method via the mpfit and lmfit implementations, and important assumptions
regarding error estimation are described here. Wrappers to use pymc and emcee
as optimizers are provided. A parallelized wrapper to fit lines in spectral
cubes is included. As part of the astropy affiliated package ecosystem,
pyspeckit is open source and open development and welcomes input and
collaboration from the community.
