Astronomical software thrives on collaboration. Many collaborations, however, are created around funded projects and remain active only for as long as that funding continues. When the funding ends, the collaboration often ends with it, while the software and its users remain.

The consequences can be that software becomes unmaintained or former partners continue development independently, creating diverging forks which causes duplicated effort and uncertainty for new users and contributors. At the same time, the cross-institutional networks built during these projects disappear, networks that provide opportunities for discussion and grounds for future collaboration.

Community collaborations such as Astropy and the IVOA demonstrate that this is not inevitable. They show that sustainable collaboration can be achieved through a variety of ways of working and funding.

This BoF will explore what makes such collaborations last and why others fail. The session will be centered around a panel discussion with a panel of experts and the audience. We will explore questions including: What enables a collaboration to survive? Which governance and maintenance models work in practice? How should responsibility be shared between individuals and institutes? And which warning signs indicate that a collaboration is unlikely to remain sustainable?

Our aim, with this discussion, is to identify commonalities between successful projects, or what makes some initiatives less successful at remaining a long-lasting collabroration. If the outcome of the discussion permits, we intend to summarise those points and submit them as an entry in the proceedings, as a reference.

Astronomy is entering an era in which several major facilities are simultaneously operating, or standing up, science platforms designed to deliver petabyte-scale data and computing to their communities. As missions and observatories move from data collection to data delivery at scale, they are independently converging on similar architectural choices — and independently running into similar operational challenges — around federated access, compute-to-data, authentication, and long-term sustainability. This BoF is proposed by confirmed panelists from Euclid/ESA Datalabs, Vera Rubin Observatory, the SKA Regional Centre Network (SRCNet), Roman Telescope, CADC/CANFAR, NASA/Fornax and LOFAR. Other platforms are invited to join the discussion to compare architectures, operational lessons, and user-facing services for large-scale science platforms and workflows.

With Euclid's Data Release 1 (DR1), a full year of Vera Rubin Observatory operations, the launch of the Roman Space Telescope, and SKA Low's science verification getting underway next year, the timing is ideal to take stock of what's working, what isn't, and where the community could converge — on topics such as federated data access, compute-to-data models, interoperability standards, and the balance between bespoke platform development and shared infrastructure. Panellists will open the session with a short position statement on how their platform is architected and operated today, before the floor opens to a moderated discussion aimed at surfacing common challenges and concrete opportunities for collaboration across observatories.