086160

The discovery of ultra-luminous X-ray pulsars openParULXPsclosePar comma i.e. comma neutron stars accreting orders of magnitude above their Eddington limit comma raised the question how these systems can become so bright. NGC 7793 P13 is one of the best systems to study to find an answer to this question comma because of its high flux comma strong pulsations and known optical counterpart. These properties allowed us to determine the full orbital ephemeris using XMM-Newton. P13 also shows a super-orbital period in the X-rays comma the origin of which is currently unknown and cannot be constrained with the existing data. Therefore we propose to continue our successful monitoring campaign of the spectrum and pulse period of P13 throughout AO 19.