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

Calculating dependencies ... done!
Dependency resolution took 1.05 s (backtrack: 0/20).

[ebuild  N     ] x11-libs/xpa-2.1.18:0/1::gentoo  USE="-doc" 880 KiB
[ebuild  N     ] x11-libs/libXScrnSaver-1.2.5::gentoo  USE="-doc" 266 KiB
[ebuild  N     ] sci-astronomy/ds9-bin-7.4-r1::gentoo  12272 KiB

Total: 3 packages (3 new), Size of downloads: 13416 KiB