  We present here the first release of the open-source python package
ExoTETHyS, which aims to provide a stand-alone set of tools for modeling
spectro-photometric observations of the transiting exoplanets. In particular,
we describe: (1) a new calculator of stellar limb-darkening coefficients that
outperforms the existing software by one order of magnitude in terms of
light-curve model accuracy, i.e., down to <10 parts per million (ppm); (2) an
exact transit light-curve generator based on the entire stellar intensity
profile rather than limb-darkening coefficients. New tools will be added in
later releases to model various effects in exoplanetary transits and eclipsing
binaries. ExoTETHyS is a reference package for high-precision exoplanet
atmospheric spectroscopy with the upcoming JWST and ARIEL missions.
