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The continued flaring activity of LS V +44 17/RX J0440.9+4431

ATEL # 2828; R. Krivonos, S. Tsygankov (IKI,MPA) A. Lutovinov (IKI), M. Turler, E. Bozzo (ISDC - University of Geneva)
on 3 Sep 2010; 17:59 UT
Password Certification: Roman Krivonos (

Subjects: X-ray, Binaries, Neutron Stars

During the Galactic latitude scan campaign performed by the INTEGRAL observatory, currently operating at the Galactic longitude of l=155 deg, we observed the brightening of a source positionally consistent with the known Be/X-ray binary LS V +44 17 (also known as RX J0440.9+4431). The source was detected at the best-fit position R.A.=04h41m08s, Decl.=44d32m24s (equinox 2000.0, uncertainty 4 arcmin). The outburst occurred at the beginning of a pointing starting on UTC 2010-09-01 05:40:22.0 and lasted approximately 2350 seconds. The mean source flux during the outburst was equal to 29.3 +/- 4.5 mCrab in the 20-60 keV band. The flux reached 76.8 +/- 17.7 mCrab at its maximum (1 mCrab in the 20-60 keV energy band corresponds to 1.24e-11 erg/s/cm2) within a time bin of 500 seconds. The average ISGRI spectrum is well described by a power-law with a photon index of 2.40+/-0.33. The source is present also in the 7-year INTEGRAL all-sky survey (Krivonos et al., 2010, arXiv:1006.4437) with an average flux of 0.95 +/- 0.15 mCrab in the 17-60 keV energy band. An activity of the Be/X-ray pulsar LS V +44 17 was recently reported elsewhere (GCN #10561, ATEL #2527, ATEL #2537). As it was mentioned in ATEL #2537, the observed short flares from this source are quite unusual for a Be/X-ray binary. The continued monitoring and multi-wavelength study of LS V +44 17 can be potentially interesting in the context of a phenomenology of such type of objects. According to the recent observations of the LS V +44 17, the source enters to the bright state accompanying by flaring activity. INTEGRAL will monitor the region of the source until 2010-09-12.

Lightcurve plot

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