A Ni'Var scientific project to develop an alternative to warp travel during the dilithium shortage, long believed by the Vulcans and Romulans to have caused the Burn.
SB-19 was an experimental means of moving ships across great distances without dilithium. The Federation pressed the scientists of Ni'Var to continue the tests despite their warnings, and when the Burn struck soon afterwards Ni'Var concluded that the experiment was responsible. The guilt and resentment led the planet to leave the Federation.
The project is the focus of the Discovery episode Unification III. Michael Burnham travels to Ni'Var to ask for the SB-19 sensor data, which could help locate the true origin of the Burn, and invokes an old rite of debate, the T'Kal-in-ket, to argue her case.
President T'Rina eventually hands over the data, and it helps Discovery trace the Burn to the Verubin Nebula.