080445

We propose a 35 ks XMM-Newton observation during the outburst of a very-faint X-ray transient. These peculiar X-ray binaries are underluminous by orders of magnitudes compared to the well-studied classical openParbrightclosePar X-ray transient population. Some of them have been identify as accreting neutron stars comma whereas only one black hole has been conclusively identified so far. However comma the nature of the vast majority remains unclear. This XMM-Newton observation will allow us to carry out a detailed spectral analysis of a very faint transient openPar< 10 performed so farclosePar in order to openPariclosePar shed light on the nature of this growing population and openPariiclosePar the reason for their sub-luminous behaviour.