Here we describe a broad overview of the Astropy project and its parts.
The “Astropy Project” is distinct from the astropy package. The Astropy Project is a process intended to facilitate communication and interoperability of python packages/codes in astronomy and astrophysics. The project thus encompasses the astropy core package (which provides a common framework), all “affiliated packages” (described below in Affiliated Packages), and a general community aimed at bringing resources together and not duplicating efforts.
The astropy package (alternatively known as the “core” package) contains various classes, utilities, and a packaging framework intended to provide commonly-used astronomy tools. It is divided into a variety of sub-packages, which are documented in the remainder of this documentation (see User Documentation for documentation of these components).
The core also provides this documentation, and a variety of utilities that simplify starting other python astronomy/astrophysics packages. As described in the following section, these simplify the process of creating affiliated packages.
The Astropy project includes the concept of “affiliated packages.” An affiliated package is an astronomy-related python package that is not part of the astropy core source code, but has requested to be included in the general community effort of the Astropy project. Such a package may be a candidate for eventual inclusion in the main astropy package (although this is not required). Until then, however, it is a separate package, and may not be in the astropy namespace.
If you are interested in starting an affiliated package, or have a package you are interested in making more compatible with astropy, the astropy core package includes features that simplify and homogenize package management. Astropy provides a package template that provides a common way to organize a package, to make your life simpler. You can use this template either with a new package you are starting or an existing package to give it most of the organizational tools Astropy provides, including the documentation, testing, and Cython-building tools. See the usage instructions in the template for further details.
To then get your package listed on the registry, take a look at the guidelines for becoming an affiliated package, and then post your intent on the astropy-dev mailing list. The Astropy coordination committee, in consultation with the community, will provide you feedback on the package, and will add it to the registry when it is approved.
Aside from the actual code, Astropy is also a community of astronomy- associated users and developers that agree that sharing utilities is healthy for the community and the science it produces. This community is of course central to accomplishing anything with the code itself. We follow the Python Software Foundation Code of Conduct and welcome anyone who wishes to contribute to the project.