2007MNRAS.382..743M

The first INTEGRAL observations of the Small Magellanic Cloud (SMC) (carried out in 2003) are reported in which two sources are clearly detected. The first source, SMC X-1, shows a hard X-ray eclipse and measurements of its pulse period indicate a continuation of the long-term spin-up now covering approximately 30 years. The second source is likely to be a high-mass X-ray binary, and shows a potential periodicity of 6.8s in the Imager on Board INTEGRAL Satellite lightcurve. An exact X-ray or optical counterpart cannot be designated, but a number of proposed counterparts are discussed. One of these possible counterparts shows a strong coherent optical modulation at ∼2.7d, which, together with the measured hard X-ray pulse period, would lead to this INTEGRAL source being classified as the fourth known high-mass Roche lobe overflow system.