Xmm–newton Observation of the Seyfert 2 Galaxy Ngc4138

The XMM–Newton data presented here are the first X–ray observation of the Seyfert 2 galaxy NGC4138. Although the galaxy has been pointed by ROSAT– HRI, it was not detected, with a flux upper limit of about 1.1×10−13 erg cm−2 s−1 in the 0.2−2.4 keV energy band1. XMM–Newton performed the observation on 26 November 2001. The source is detected for the first time in X–rays with F0.2−2.4 = 1.0 × 10−13 erg cm−2 s−1, in agreement with the upper limit of ROSAT 1. The source spectrum is typical of Seyfert 2 galaxies. We find heavy obscuration (NH ≈ 8 × 1022 cm−2) and a flat photon index (≈ 1.6). The source intrinsic luminosity is about 5× 1041 erg/s in the 0.5− 10 keV energy band.