THE HUNT FOR NEW PULSAR ULTRALUMINOUS X-RAY SOURCES: NGC7090 ULX

Following a series of remarkable recent discoveries, we now know that some ofthe most luminous members of the ULXray source population are actually poweredby highly superEddington neutron stars. Five such systems are now known, butbased on the longterm variability characteristics exhibited by these sources,we have compiled a sample of 19 additional ULX pulsar candidates from thebroader ULX population. Here we propose a coordinated target of opportunityobservation with XMM (100ks) and NuSTAR (100ks) of one of the most promising ofthese candidates, NGC7090 ULX, when the source is bright. Our main aims are tosearch for pulsations in order to test our prediction that this is another ULXpulsar, and constrain the broadband spectrum. truncated!, Please see actual data for full text [truncated!, Please see actual data for full text]