Discovery of a 220 second X-ray pulsar, AX J1749.2-2725

We report here the discovery of a faint 220 s X-ray pulsar, AX J1749.2-2725 , with ASCA. In the analysis, we used a method that can detect a pulsating source in a field of view contaminated by stray light. The source was obser ved on four occasions between 1995 March and 1997 September. The observed s ource flux was similar to 3.0 x 10(-11) ergs s(-1) cm(-2) (2-10 keV) in 199 5 March and became an order of magnitude fainter during the 2.5 yr interval . We cannot rule out the possibility that AX J1749.2 - 2725 is a nearby (d less than or similar to 1.3 kpc) DQ Her-type white dwarf binary, while the hard X-ray spectrum and the transient behavior suggest that it is a distant (d similar to 8.5 kpc) binary system containing a neutron star.