In this series of posts, we sit down with a few keynote speakers of the 245th AAS meeting to learn more about them and their research. You can see a full schedule of their talks here and read our other interviews here!
From performing coordinate transformations to modeling and visualizing data, Astropy is a community-driven, open-source Python package that has become an indispensable tool for astronomers. The Astropy Collaboration has been honored with the 2025 Berkley Prize, recognizing its transformative impact on the field. Erik Tollerud, Kelle Cruz, and Clara Brasseur, members of the Astropy coordination team, are accepting the award on behalf of the collaboration and will be giving the closing plenary lecture at AAS 245. We had the opportunity to speak with them about Astropy and software development in astronomy.



In the early 2010s, multiple Python packages for astronomy were being developed, including one by Erik, who was a graduate student back then. “Do we really need to create yet another library? Maybe we should coordinate our efforts,” recalls Erik, referencing a conversation on a mailing list that sparked an effort to bring developers together. “This led to us all having a meeting,” Kelle continues, where the groundwork for Astropy was laid. “And from there, basically, it all snowballed,” says Erik.
The Astropy community today consists of several members from around the globe who contribute to the project in various ways. “(Astropy) was built on the backs of volunteers,” says Clara Brasseur, who started their journey with Astropy while they were working as a software engineer at the Space Telescope Science Institute (STScI). Clara is currently a final year PhD student at the University of St. Andrews working on the magnetic fields of young, low-mass stars. Working on Astropy is “the main way I give back to the astronomy community.” They are also involved in Astropy Learn, which aims to develop guides and tutorials on Astropy. “The Learn arm is really important,” says Clara, adding, “I’ve become even more interested in it since going back to school as a grad student.”
Kelle Cruz, an associate professor at Hunter College, CUNY, has transitioned from researching low-mass stars and brown dwarfs to focusing on software development. They are currently developing a toolkit “to make it easier for astronomers to make their own databases.” It is called the AstroDB Toolkit, and Kelle describes it as the “Astropy for databases.” The beta test of this project is the SIMPLE archive, a collaborative database of information about low-mass stars.
Advice for getting into software development
For students interested in software development, Kelle suggests starting by “putting your code on Github, talking to people who are doing software development, and implementing it into your own research.” There are a lot of skills to learn, but they advise students to start small by practicing software engineering skills and approaching them from an open science and reproducible science mindset. Clara adds that you should start practicing reproducibility of your code using GitHub with version control and “think early on about making your code publicly available.” They believe practicing this early will help later when working on projects with multiple contributors. “It is helpful to have already practiced that concept,” says Clara.
Another important aspect of software development is the “community and human elements,” according to Erik. “Working in a software setting is often as much about human connection and teamwork as it is about actual software.” They also advise, “Don’t worry too much about relevant experience”. Instead, focus on identifying a niche to demonstrate your value to your potential employers. “A lot of what astronomers do overlap with software development work,” Erik adds.
Contributing to Astropy
Astropy currently has a constellation of affiliated packages and is looking to grow in this area. The team’s goals include identifying gaps in the software capabilities researchers need and filling them with affiliated packages. They are also looking for contributors who have built something useful and exciting that the community appreciates, to bring those projects into the Astropy ecosystem.
“There’s a lot of ways to get involved”, says Kelle, from implementing new features, and testing tools to closing issues. There are also funding opportunities available for new contributors. The Astropy team is also keen on expanding their Learn resources – a suite of Jupyter notebook tutorials suitable for undergraduate classrooms. “We are currently working on having an infrastructure that allows scientists and teachers to contribute their learning materials” for Astropy Learn. You can learn more about contributing a tutorial notebook to Astropy Learn here. If you want to get involved with Astropy, check out their Slack workspace.
Join Erik Tollerud, Kelle Cruz, and Clara Brasseur on Thursday, January 16, 2025, at 4:40 PM ET for the Lancelot M. Berkeley − New York Community Trust Prize for Meritorious Work in Astronomy Lecture, and learn about the history, current status and future of Astropy
Edited by Sowkhya Shanbhog
Featured Image Credit: AAS