088403

A new ULX was recently discovered in the nearby galaxy NGC 3621 in the archivalXMM-Newton data which shows extremely marked variability - unique among theknown ULXs - reminiscent of the so-called heartbeats a type of variabilitypattern observed in only a handful of systems. The archival data yieldedcontradictory information on the nature of the compact object powering XMMJ111816.0-324910 partly due to the limited quality of the data and to thelimited understanding of the heartbeat phenomenon. We propose a Target ofOpportunity observation of XMM J111816.0-324910 for a total of 120ks to obtaina better understanding of the properties of J1118 by means of detailed spectraland timing analysis. This ToO will be triggered based on approved Swift observations. [truncated! Please see actual data for full text]