2000ApJ...534L.181S

A new pulsating X-ray source, AX J183220-0840, with a 1549.1 s period was discovered at R.A.=18^h32^m20^s and decl.=-8°40'30'' (J2000, with an uncertainty of 0'.6) during an ASCA observation on the Galactic plane. The source was observed two times, in 1997 and in 1999. A phase-averaged X-ray flux of 1.1x10^–11 ergs.cm^–2.s^–1 and a pulsation period of 1549.1±0.4 s were consistently obtained from these two observations. The X-ray spectrum was represented by a flat, absorbed power law with a photon index of Γ≃0.8 and an absorption column density of N_H≃1.3x10²² cm^–2. Also, a signature of iron K-shell line emission with a centroid of 6.7 keV and an equivalent width of approximately 450 eV was detected. From the pulsation period and the iron-line feature, AX J183220-0840 is likely to be a magnetic white dwarf binary with a complexly absorbed thermal spectrum with a temperature of about 10 keV.