These are the packages that would be merged, in order:

Calculating dependencies ... done!
Dependency resolution took 0.98 s (backtrack: 0/20).

[ebuild  N     ] sci-astronomy/swarp-2.41.5::gentoo  USE="threads -cfitsio -doc" 434 KiB

Total: 1 package (1 new), Size of downloads: 434 KiB