Unveiling the nature of RX J0002+6246 with XMM-Newton

The X-ray source RX J0002+6246 was discovered close to the supernova remnant CTB 1 in a ROSAT observation performed in 1992. The source phenomenology (soft spectrum, apparent lack of counterparts, possible pulsations at 242 ms, hints for surrounding diffuse emission) led to interpret it as an isolated neutron star in a new supernova remnant. We have analysed an archival XMM - Newton observation performed in 2001. The source coordinates, as computed on the XMM - Newton images, coincide with those of a bright source listed in optical and infrared catalogues. The X-ray spectrum is well described by an optically thin plasma model. No fast pulsations are seen nor clear evidence of a supernova remnant associated to the source. Thus, we conclude that RX J0002+6246 is not an isolated neutron star, but the X-ray counterpart of the bright optical/infrared source, most likely a F7 spectral class star located at about 0.2 kpc.