A 168-s X-Ray Pulsar in the Small Magellanic Cloud Observed with ASCA

We report on the detection of 167.8 ± 0.2\,s pulsations from AX J0052.9$-$7157 in the Small Magellanic Cloud with ASCA. The pulsations show an energy-independent sinusoidal profile. The X-ray spectrum has been described by an absorbed hard power-law (photon index ~ 0.7) with a luminosity of ~ 8.8 × 10³⁵\,erg\,s⁻¹ at a distance of 60\,kpc. The position is determined to be (R.A.,~Dec.)J2000 = (00ʰ52ᵐ59.ˢ2, -7171∘57^58^), with an error radius of ~ 30^. We have found that a variable Be/X-ray binary RX J0052.9$-$7158 is located within the 30^ error circle, and is also located at the edge of the 10^ error circle of the 169-s pulsar XTE J0054$-$720. We therefore conclude that these are the same source, a Be/X-ray binary pulsar.