CUSUMANO, GIANCARLOGIANCARLOCUSUMANOLA PAROLA, VALENTINAVALENTINALA PAROLASEGRETO, ALBERTOALBERTOSEGRETOD'AI', ANTONINOANTONINOD'AI'2020-05-122020-05-1220160035-8711http://hdl.handle.net/20.500.12386/24747IGR J16195-4945 is a hard X-ray source discovered by INTEGRAL during the Core Programme observations performed in 2003. We analysed the X-ray emission of this source exploiting the Swift-Burst Alert Telescope (BAT) survey data from 2004 December to 2015 March, and all the available Swift-X-ray Telescope (XRT)-pointed observations. The source is detected at a high significance level in the 123-month BAT survey data, with an average 15-150 keV flux of the source of ∼1.6 mCrab. The timing analysis on the BAT data reveals with a significance higher than six standard deviations the presence of a modulated signal with a period of 3.945 d, that we interpret as the orbital period of the binary system. The folded light curve shows a flat profile with a narrow full eclipse lasting ∼3.5 per cent of the orbital period. We requested phase-constrained XRT observations to obtain a more detailed characterization of the eclipse in the soft X-ray range. Adopting reasonable guess values for the mass and radius of the companion star, we derive a semimajor orbital axis of ∼ 31 R<SUB>☉</SUB>, equivalent to ∼1.8 times the radius of the companion star. From these estimates and from the duration of the eclipse, we derive an orbital inclination between 55 and 60 deg. The broad-band time-averaged XRT+BAT spectrum is well modelled with a strongly absorbed flat power law, with absorbing column N<SUB>H</SUB> = 7 × 10<SUP>22</SUP> cm<SUP>-2</SUP> and photon index Γ = 0.5, modified by a high energy exponential cutoff at E<SUB>cut</SUB> = 14 keV.STAMPAenArticle10.1093/mnras/stv28512-s2.0-84964432727000372265200033https://academic.oup.com/mnras/article/456/3/2717/11008502016MNRAS.456.2717CFIS/05 - ASTRONOMIA E ASTROFISICAERC sectors::Physical Sciences and Engineering::PE9 Universe sciences: astro-physics/chemistry/biology; solar systems; stellar, galactic and extragalactic astronomy, planetary systems, cosmology, space science, instrumentation