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A strong X-ray outburst was detected in HE1136-2304 in 2014. Accompanyingoptical spectra revealed that the spectral type has changed from a nearlySeyfert 2 type (1.95), classified by spectra taken 10 and 20 years ago, to aSeyfert 1.5 in our most recent observations. We seek to investigate a detailedspectroscopic campaign on the spectroscopic properties and spectral variabilitybehavior of this changing look AGN and compare this to other variable Seyfertgalaxies. We carried out a detailed spectroscopic variability campaign ofHE1136-2304 with the 10 m Southern African Large Telescope (SALT) between 2014December and 2015 July. The broad-line region (BLR) of HE1136-2304 isstratified with respect to the distance of the line-emitting regions. Theintegrated emission line intensities of Halpha, Hbeta, HeI 5876, and HeII 4686originate at distances of 15.0 (+4.2,-3.8), 7.5 (+4.6,-5.7), 7.3 (+2.8,-4.4),and 3.0 (+5.3,-3.7) light days with respect to the optical continuum at 4570AA.The variability amplitudes of the integrated emission lines are a function ofdistance to the ionizing continuum source as well. We derived a central blackhole mass of 3.8 (+-3.1) 10exp(7) M_solar based on the line widths anddistances of the BLR. The outer line wings of all BLR lines respond much fasterto continuum variations indicating a Keplerian disk component for the BLR. Theresponse in the outer wings is about two light days shorter than the responseof the adjacent continuum flux with respect to the ionizing continuum flux. Thevertical BLR structure in HE1136-2304 confirms a general trend that theemission lines of narrow line active galactic nuclei (AGNs) originate at largerdistances from the midplane in comparison to AGNs showing broader emissionlines. Otherwise, the variability behavior of this changing look AGN is similarto that of other AGN.

Broad-line region structure and line profile variations in the changing look AGN HE1136-2304