I know I prolly shoulda brought this up back in 2009, but is there a reason why Explorators need access to Scholastic Lore (Astromancy) +10 twice? I see it in their Rank 2 and Rank 4 advances. (They get training in SL:As at Rank 1, and +20 Mastery at Rank 5...) Core book, pp. 53-54.

It's almost certainly a misprint, but it's not ENTIRELY worthless this way because there's one very specific circumstance in which this would be useful.

If the Explorator took an Alternate Career at Rank 2 (say to Xenographer), then Scholastic Lore Astromancy +10 under the basic rules should now cost 400XP. If s/he then reaches Rank 4 as an Explorator, it would become available again at 200XP.

Good point. But, looking at all the errata on the Explorator advances that involve doubles, I'm'a guess that this is, indeed, an error. Mostly, I'm just curious where the advance belongs.