Provide a known mapping between input visit and tract, patch

[wmwv]

@johannct already creates an sqlite file with this information to do the processing in the first place. This is then transferred over to NERSC as part of the repo.

We can expose this as a table or query interface

[wmwv]

@bechtol This is the easy way. A full RA, Dec interface would take a little more work.

[johannct]

let me know if the db should evolve to something usable by more people. I gave 0 thought to its content/schema/naming, and just hacked quickly what I needed.

[wmwv]

Thanks, @johannct . It looks perfect and simple as it is.

My suspicious is that anything more sophisticated should come from DM Science Pipelines Gen 3 Butler. Even if that ends up not providing the exact thing we need, I suspect it will be a much easier base to build on.

[yymao]

I am bumping the priority to medium and labeling it "help wanted" since this is one of the most asked questions.