Our timeline for coming up with a plan is end of April. The motivations are:
- Does adopting Astropy make us more efficient at coding and let us focus on the LSST-specific issues without having to support general packages? Will we be able to do more for less?
- Will the learning curve be lower for new developers if we use commonly accepted Python codebases?
- Would we see broader adoption in the community for our software if they were based on Astropy?
- Would Level 3 adoption be significantly easier and more popular if Astropy-compatible APIs were available?
- If we publish some of our packages as Astropy affiliated packages (which by definition means we use astropy interfaces internally) would this encourage more contributions from external developers/scientists?
As for longevity, JWST are entirely based on Astropy so there is a clear support pathway for at least 10 years. The code is BSD-licensed and open source so will not disappear at that time. It also has a huge mindshare in the general astronomy community.
My understanding is that at minimum only option 1 can be justified by MREFC funding. Provision of Astropy-compatible APIs could be justified as part of the general Level 3 design (L3 does not mandate that we just use Level 2 codebase).