NICER observation list: Target ID 461601

Quasi-Periodic Eruptions (QPEs) are a very peculiar new class of X-ray sources and their origin is still unknown. We aim to test one of the proposed scenarios, i.e. a small compact object orbiting the central super-massive black hole, by monitoring the period evolution of one known QPE source, which was already observed with NICER on August 2020. Our scientific goal can be achieved performing 2 sets of 10 days of observations separated by a few months, with each set consisting of 12 visits per day, each with an exposure of 500s, for a total of ~120ks. In this way we can either rule out the model, e.g. if a period increase is observed, or put constraints on the mass and eccentricity of the possible second orbiting body.