coronagraph is an open-source Python package for generalized telescope noise modeling for extrasolar planet (exoplanet) science. This package is based on Interactive Data Language (IDL) code originally developed by T. Robinson, and described in detail with science applications in Robinson, Stapelfeldt & Marley (2016). The model uses analytic relations to calculate the photon count rates for a variety of astrophysical, telescope, and instrumental noise sources. These include photons from coronagraph speckles, zodiacal and exozodiacal dust, telescope thermal emission, dark current, read noise, and clock-induced charge. Photons from a user-provided exoplanet source spectrum are compared against sources of noise to provide wavelength-dependent signal-to-noise (S/N) ratios and synthetic observations. The model also features "reverse" S/N calculations, which provide the requisite exposure times per wavelength interval such that a user-specified S/N is achieved on the exoplanet spectrum.