We report the results of a 1998 July Beppo SAX observation of a field in the Small Magellanic Cloud ( SMC ) which led to the discovery of \sim 345 s pulsations in the X–ray flux of SAX J0103.2–7209 .
The Beppo SAX X–ray spectrum is well fit by an absorbed power–law with photon index \sim 1.0 plus a black body component with kT = 0.11 keV .
The unabsorbed luminosity in the 2–10 keV energy range is \sim 1.2 \times 10 ^ { 36 } erg s ^ { -1 } .
In a very recent Chandra observation the 345 s pulsations are also detected .
The available period measurements provide a constant period derivative of –1.7 s yr ^ { -1 } over the last three years making SAX J0103.2–7209 one of the most rapidly spinning–up X–ray pulsars known .
The Beppo SAX position ( 30″ uncertainty radius ) is consistent with that of the Einstein source 2E 0101.5–7225 and the \R source RX J0103.2–7209 .
This source was detected at a luminosity level of few 10 ^ { 35 } –10 ^ { 36 } erg s ^ { -1 } in all datasets of past X–ray missions since 1979 .
The \R HRI and Chandra positions are consistent with that of a m _ { V } = 14.8 Be spectral type star already proposed as the likely optical counterpart of 2E 0101.5–7225 .
We briefly report and discuss photometric and spectroscopic data carried out at the ESO telescopes two days before the Beppo SAX observation .
We conclude that SAX J0103.2–7209 and 2E 0101.5–7225 are the same source , a relatively young and persistent X–ray pulsar in the SMC .