INTEGRAL pointed observation of XTEJ1817-330

We report preliminary results of the INTEGRAL ToO observation of the transient BHC XTEJ1817-330 (ATEL #714, #731) performed from 2006-02-15 01:28:29 (U.T.C.) to 2006-02-17 11:19:41.0 for a total exposure time of about 200 ksec. The source has been clearly detected up to 200 keV with no apparent cutoff at flux levels of about 1 Crab (3-20 keV) and 90 mCrab (20-200 keV).

Preliminary analysis of JEM-X and IBIS/ISGRI data show that the 3-200 keV spectrum of the source can be well fitted by a disk black body with temperature of 0.9 keV plus a powerlaw with photon index 2.7. In agreement with previous reports (ATEL #724, #733, #740), no interstellar absorption was needed in the fit, suggesting a low column density (Nh~10^21 cm^-2).

The power density spectrum, computed from the 3-15 keV JEM-X light curve, is consistent with white noise above ~1 mHz, while it is well represented by a power law with index ~2.07 below 1mHz. We estimate the RMS fractional amplitude to be ~6% between 0.01mHz and 1mHz. The relative weakness of the hard component and the low level of variability suggest that the source has been observed predominantly in the high/soft state, although some evolution could be seen.

We also searched for signatures of 511 keV emission features in 3 hour-long sections of the SPI data as well as on the entire observation. No emission was detected with 3 sigma upper limits respectively of 2.4e-3 ph/cm^2/s and 7.5e-4 ph/cm^2/s. XTEJ1817-330 will be observed regularly by INTEGRAL in the following weeks by the Galactic Bulge Monitoring Program (ATEL #734, #738).

Further observations are encouraged to follow the evolution of this source.