Context :

Aims : The galactic black hole candidate XTE J1817-330 was discovered in outburst by RXTE in January 2006 .
We present here the results of an XMM-Newton Target of opportunity observation ( TOO ) , performed on 13 March 2006 ( 44 days after the maximum ) , and an INTEGRAL observation performed on 15-18 February 2006 ( 18 days after the maximum ) .

Methods : The EPIC-pn camera on-board XMM-Newton was used in the fast read-out Burst mode to avoid photon pile-up , while the RGSs were used in Spectroscopy high count rate mode .
We fit both the XMM-Newton and the INTEGRAL spectra with a two-component model consisting of a thermal accretion disk ( represented by diskbb or diskpn models ) and a comptonizing hot corona ( represented by a power-law or the compTT model ) .

Results : The soft X-ray spectrum is dominated by an accretion disk component , with a maximum temperature decreasing from 0.96 \pm 0.04 \mbox { keV } at the time of the INTEGRAL observation to 0.70 \pm 0.01 \mbox { keV } on 13 March .
The Optical Monitors on board INTEGRAL and XMM-Newton showed the source with magnitudes V : 11.3–11.4 , U:15.0–15.1 and UVW1:14.7–14.8 .
The soft X-ray spectrum , together with the optical and UV data , show a low hydrogen column density towards the source , and several absorption lines , most likely of interstellar origin , are detected in the RGS spectrum : OIK \alpha , OIK \beta , OII , OIII and OVII , which trace both cold and hot components of the ISM .
The soft X-ray spectrum indicates the presence of a black hole , with an estimate for the upper limit of the mass of 6.0 ^ { +4.0 } _ { -2.5 } M _ { \odot } .

Conclusions :