Peace,
now it is now back
on a Russian network again:
# ORG: (RU) ORG-FG2-RIPE "OOO FREEnet Group"
Ronald, as you correctly mention later in the message, the 15.0/24 block was probably leased away _long_ ago (as we assume that a research institute hardly needs /16 IPv4 to operate).
Meanwhile the 193.233.15.0/24 sub-block is being routed by AS42745
aka "Safe Value Limited"
The only provider for the latter being Voxility Inc., California, USA.
I guess you'd need to repeat your feat once again, now again with an American company :-)
--
Töma