086401

PSR J1023+0038 is a binary system that hosts a neutron star and a low-mass comma main-sequence companion star. It has been observed to switch on timescales of years between a radio millisecond pulsar and a disc-dominated state comma of uncertain origin. After its last switch to a disc-dominated state in 2013 comma the source has been the object of extensive multi-wavelength monitoring campaigns comma during which the continuous switch between three X-ray modes openParhigh comma low and flareclosePar on timescales of 10 s has been observed. Here we propose the ultimate comma strictly simultaneous comma multi-wavelength campaign to study in detail this unique phenomenon. We will involve NuSTAR comma XMM-EPIC comma Swift-UVOT comma XMM-OM comma VLT-HAWK-I comma VLA observations to probe models using correlations and lags comma as well as to study the pulsed signal.