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We discuss BeppoSAX observations and archive ASCA data of NGC 7679, a nearby,nearly face-on SB0 galaxy in which starburst and AGN activities coexist. TheX-ray observations reveal a bright (L_{0.1-50 keV} \sim 2.9 \times 10^{43} ergs^{-1}) and variable source having a minimum observed doubling/halving timescale of \sim 10 - 20 ksec. A simple power law with photon index of \Gamma \sim1.75 and small absorption (N_H < 4\times 10^{20} cm^{-2}) can reproduce the NGC7679 spectrum from 0.1 up to 50 keV. These X-ray properties are unambiguoussigns of Seyfert 1 activity in the nucleus of NGC 7679. The starburst activity,revealed by the IR emission, optical spectroscopy and H\alpha imaging, anddominating in the optical and IR bands, is clearly overwhelmed by the AGN inthe X-ray band. Although, at first glance, this is similar to what is observedin other starburst-AGN galaxies (e.g. NGC 6240, NGC 4945), most strikingly hereand at odds with the above examples, the X-ray spectrum of NGC 7679 does notappear to be highly absorbed. The main peculiarity of objects like NGC 7679 isnot the strength of their starburst but the apparent optical weakness of theSeyfert 1 nucleus when compared with its X-ray luminosity. To date NGC 7679 isone of the few Seyfert 1/ Starburst composites for which the broad-band X-rayproperties have been investigated in detail. The results presented here implythat optical and infrared spectroscopy could be highly inefficient in revealingthe presence of an AGN in these kinds of objects, which instead is clearlyrevealed from X-ray spectroscopic and variability investigations.Comment: 10 pages, 4 figures, Latex manuscript, Accepted for publication in  the Astronomy and Astrophysics - Main Journa

Unveiling the AGN powering the "Composite" Seyfert/Star-forming galaxy NGC 7679: BeppoSAX and ASCA results