Volume 15 would be the Japanese edition from Big Comics, and is the equivalent volume to Viz's Volume 1 of the "Eternity" storyline. BC are up to volume 21 "Ginga Tetsudo Monogatori" which contains the side-story that lies behind the recent "Galaxy Railways" Anime. Viz are now two volumes behind (and flipped to boot! What - they think no-one will notice that two of the main characters have distinctive facial scarring on the *left* suddenly on the *right*?!!) ;-P However the Viz translation also leaves a *lot* to be desired in places...
If you read French, Kana, the French publishers who translated the Space Pirate Captain Harlock and Nibelung no Yubia ("Harlock Saga") manga, are translating GE999, but I'm not sure whether or not they started with the original series or not, postage from Amazon.fr being bleeping expensive - and me only on the other side of the channel! (and since the Japanese is furigana'd, not much point in buying a French copy to read! I already made *that* mistake with Versailles no Bara...)
The Japanese currently have at least two editions in print of the original series (Usually distinguished as the "Andromeda" storyline )- I've got the tiny, pocket sized Shonen Gahosha Bunko edition which runs vols 1-12 - and is gratifiyingly furigana'd for kanji-deficient novices... <g> Big Comics runs a smaller page count but a larger print size in 14 volumes (no idea if they're furigana'd though... editions can vary!) It's this latter edition that started the 'Eternity' Series directly after the orginal!
If anyone cares, a tankobun called "Space Natural History Mars Hotel" seems to be set during the Eternity Series, and Tetsurou, Maetel and Harlock show up for a few chapters - since this one turned up on my radar out of the blue, there could be a few other side-stories lurking out there that add to the story (which is getting more convoluted by the volume! He does like to waffle on, does Leiji-san...!)
H