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Two faint X-ray pulsars, AX J2725 and AX J2733, located in the direction of the Galactic Centre, were studied in detail using data from the INTEGRAL, XMM- Newton and Chandra observatories in X-rays, the SOFI/NTT instrument in the infrared and the RTT150 telescope in the optical. X-ray positions of both sources were determined with an uncertainty better than arcsec, which allowed us to identify their infrared counterparts. From the subsequent analysis of infrared and optical data, we conclude that the counterparts of both pulsars are likely to be massive stars of B0-B3 class located behind the Galactic Centre at distances of 12-20 kpc, depending on the type, probably in the further parts of the Galactic spiral arms. In addition, we investigated the extinction law towards the Galactic bulge and found that it is significantly different from the standard one. [ABSTRACT FROM AUTHOR]

We are reporting the discovery of X-ray pulsations from the source AXJ1749.1-2733 with the period of ∼132 s based on the XMM–Newton data obtained in 2007 March. The observed pulse profile has a double-peaked structure with the pulse fraction of about 25–30 per cent in the 3–10 keV energy band. We have also found that a periodicity with practically the same period has been detected from the source by the IBIS telescope onboard the INTEGRAL observatory during an outburst on 2003 September 9 in the 20–50 keV energy band. Due to the double-peaked pulse profile, there is an additional peak on both periodograms of ∼66 s; therefore we have also investigated the possibility that the last value is the true pulse period. The source spectrum obtained by the XMM–Newton observatory in the soft energy band is being heavily absorbed ( NH≃ 2 × 1023 cm−2) due to a strong intrinsic absorption in the binary system that leads to the conclusion that AXJ1749.1-2733 is a new transient X-ray pulsar in the high-mass X-ray binary system. [ABSTRACT FROM AUTHOR]