Ludovko IX was the inhabited ninth planet in its system. This planet was home to the R'M'Yr B'rneht Institute, which was credited with developing the explosive Bishop/P 374. (TNG: "Night Terrors", display graphic)
This planet was only mentioned in writing.
For the remastered episode "Night Terrors", the list of explosives was revised. This planet was mentioned in one of the new entries.