Catalogs are still CHIME-specific

[rikvl]

When generating the catalogs, we do perform some modest filtering of sources:

1. Sources with declination < -20 degrees are excluded.

2. Sources without flux measurements on both sides of the CHIME band are excluded.

So the catalogs are relevant to northern hemisphere experiments operating in the CHIME band. I could generate new catalogs without these filters. Removing (1) is straightforward and will simply increase the catalog size. For (2), we could handle cases requiring extrapolation by raising a warning or error when flux is requested at a frequency outside the measured range.

I wasn’t aware of hfbcat before. From looking at the code, it seems logical to group it with fluxcat in the new repository, but I’ll defer to @rikvl and @arashcosmology for the final decision.

Originally posted by @ssiegelx in #89

The HFB catalog uses the following filtering:

1. Sources with declination < -10 are excluded
2. Absorption features that fall outside the CHIME band are excluded
3. Absorption features that fall in RFI bands at first light are excluded

I think I can regenerate the "HFB target list" and maybe also give it a more appropriate name.