Palps actually erased the minds of the people of Courscant not Byss, though on Byss he did dominate their minds too.
Could the Emperor's power through the dark side of the Force have been sufficient to compel thousands or millions of people to forget having seen the Lusankya being buried?Source: X-Wing: Krytos Trap
She renamed the vessel Lusankya, and, with help from the Emperor’s mind-fogging powers, Imperial engineers buried the tremendous battleship beneath the cityscape in Coruscant’s Manarai Mountain district.Source: The New Essential Guide to Characters
The Byss feat is this one
Almost mindless under the oppression of the Emperor's dark side influence, the people of Byss find their life energies constantly leeched off during the Emperor's vile machinations.Source: The Dark Empire Endnotes