1RXS J214303.7+065419/RBS 1774: A new isolated neutron star candidate

We report on the identification of a new possible Isolated Neutron Star can didate in archival ROSAT observations. The source 1RXS J214303.7+065419, li sted in the ROSAT Bright Source Catalogue as RBS 1774, is very soft, exhibi ts a thermal spectrum well fitted by a blackbody at T similar to 90 eV and has a low column density, N-H similar to 5 x 10(20) cm(-2). Catalogue searc hes revealed no known sources in other energy bands close to the X-ray posi tion of RBS 1774. Follow-up optical observations with NTT showed no peculia r object within the X-ray error circle. The absence of any plausible optica l counterpart down to m(R) similar to 23 results in an X-ray to optical flu x ratio in excess of 1000.