Investigating an extreme ULX detected in eRASS1

The detection of pulsating ultraluminous Xray sources (PULXs) has led to aparadigm shift for the field; the key questions now revolve around thedemographics of ULXs (black holes vs neutron stars) and the details of theiraccretion physics. The detection of more PULXs is critical to answering bothquestions. We have therefore mined the first eROSITA allsky survey (eRASS1)with the intention of finding new PULX candidates. Here, we propose a 30 ksobservation of a new extreme ULX (L(X) > 10^40 erg/s) detected in each ofeRASS1, 2 and 3 with a high enough flux to make sensitive accelerated pulsationsearches very viable, and thus determine whether it is a PULX. truncated!, Please see actual data for full text [truncated!, Please see actual data for full text]