Fortran >:D

For low-level, fair. I only know of people in astronomy academia who actually use it nowadays though.

There are good technical reasons to use Fortran even in 2022. For example, it avoids** is aliasing (pointers / references / etc.). This allows for some kinds of optimizations impossible in most other languages.

It's used in a bunch of small niches, but it has users beyond just astronomy.

** A million disclaimers apply.

I am aware that hypothetically fortran code is the fastest possible. That said, I am not sure how great this aliasing difference is in practice.

There is a reason why most BLAS implementations have been rewritten into C.

Signal processing stuff is still sometimes written in it.