Developed by the Antiquarian Engineering Department; the Tachyon is a form of homing device. To the casual observer it looks like a watch, but internally it contains a quantum singularity. The Antiquarians have harnessed the gravitational anomalies found at the heart of a black hole and encapsulated them within a small chronometer, giving the user the power to jump back up to 2 minutes into the past without the need for a Vestige (an object with an appropriate history). It also can be programmed to bookmark key points in time, allowing the user to return to the present when working in the distant past.
The Tachyon watch face consists of a series of concentric dials, each marked with temporal symbols that can display the time using the Holocene Calendar (spanning 10,000 years). There are also two buttons along the side: one that allows the user to rewind the last two minutes and the other to take the user back to the most recent moment in the present (also known as the Frontier).
Tachyons should only work in the presence of a member of the Oblivion Order, alongside the Almanac, the Tachyon is one of the ways that the Order can keep track of their agents. Losing a Tachyon is a very serious offence. Going back into the past without one is seen as suicide as it one of the only ways to get back into the present.