We report the discovery of a bright X-ray transient object , XMMU J174554.4 $ - $ 285456 , observed in outburst with XMM-Newton on October 3 , 2002 , and located at 6.3 ^ { \prime } from Sgr A* , the supermassive black hole at the Galactic center .
This object exhibits a very large X-ray luminosity variability of a factor of about 1 300 between two X-ray observations separated by four months .
The X-ray spectrum is best fitted by a power-law with a photon index of 1.6 \pm 0.2 and absorption column density of 14.1 ^ { +1.6 } _ { -1.4 } \times 10 ^ { 22 } cm ^ { -2 } .
This large absorption suggests this source is located at the distance of the Galactic center , i.e. , 8 kpc .
The 2–10 keV luminosity is about 1.0 \times 10 ^ { 35 } ( d / { 8 kpc } ) ^ { 2 } erg s ^ { -1 } .
A pulsation period of about 172 s is hinted by the timing analysis .
The X-ray properties strongly suggest a binary system with either a black hole or a neutron star for the compact object .