Dear colleagues, We are very happy to announce the v4.1 release of the Astropy package, a core Python package for Astronomy: http://www.astropy.org Astropy is a community-driven Python package intended to contain much of the core functionality and common tools needed for astronomy and astrophysics. It is part of the Astropy Project, which aims to foster an ecosystem of interoperable astronomy packages for Python. New and improved major functionality in this release includes: * A new SpectralCoord class for representing and transforming spectral quantities * Support for writing Dask arrays to FITS files * Added True Equator Mean Equinox (TEME) frame for satellite two-line ephemeris data * Support for in-place setting of array-valued SkyCoord and frame objects * Change in the definition of equality comparison for coordinate classes * Support use of SkyCoord in table vstack, dstack, and insert_row * Support for table cross-match join with SkyCoord or N-d columns * Support for custom attributes in Table subclasses * Added a new Time subformat unix_tai * Added support for the -TAB convention in FITS WCS * Support for replacing submodels in CompoundModel * Support for units on otherwise unitless models via the Model.coerce_units method. * Support for ASDF serialization of models In addition, hundreds of smaller improvements and fixes have been made. An overview of the changes is provided at: http://docs.astropy.org/en/stable/whatsnew/4.1.html Instructions for installing Astropy are provided on our website, and extensive documentation can be found at: http://docs.astropy.org If you usually use pip/vanilla Python, you can do: pip install astropy --upgrade If you make use of the Anaconda Python Distribution, soon you will be able update to Astropy v4.1 with: conda update astropy Or if you cannot wait for Anaconda to update their default version, you can use the astropy channel: conda update -c astropy astropy Please report any issues, or request new features via our GitHub repository: https://github.com/astropy/astropy/issues Nearly 400 developers have contributed code to Astropy so far, and you can find out more about the team behind Astropy here: https://www.astropy.org/team.html The LTS (Long Term Support) version of Astropy at the time of v4.1's release is v4.0 - this version will be maintained until next LTS release (v5.0, scheduled for Fall 2021). Additionally, note that the Astropy 4.x series only supports Python 3. Python 2 users can continue to use the 2.x series but it is no longer supported (as Python 2 itself is no longer supported). For assistance converting Python 2 code to Python 3, see the Python 3 for scientists conversion guide. If you use Astropy directly for your work, or as a dependency to another package, please remember to acknowledge it by citing the appropriate Astropy paper. For the most up-to-date suggestions, see the acknowledgement page, but as of this release the recommendation is: This research made use of Astropy, a community-developed core Python package for Astronomy (Astropy Collaboration, 2018). We hope that you enjoy using Astropy as much as we enjoyed developing it! Erik Tollerud v4.1 Release Coordinator on behalf of The Astropy Project https://www.astropy.org/announcements/release-4.1.html