  IGR J17544-2619 and XTE J1739-302 are considered the prototypical sources of
the new class of High Mass X-ray Binaries, the Supergiant Fast X-ray Transients
(SFXTs).These sources were observed during bright outbursts on 2008 March 31
and 2008 April 8, respectively, thanks to an on-going monitoring campaign we
are performing with Swift, started in October 2007. Simultaneous observations
with XRT and BAT allowed us to perform for the first time a broad band
spectroscopy of their outbursts. The X-ray emission is well reproduced with
absorbed cutoff powerlaws, similar to the typical spectral shape from accreting
pulsars. IGR J17544-2619 shows a significantly harder spectrum during the
bright flare (where a luminosity in excess of 1E36 erg/s is reached) than
during the long-term low level flaring activity (1E33-1E34 erg/s), while XTE
J1739-302 displayed the same spectral shape, within the uncertainties, and a
higher column density during the flare than in the low level activity. The
light curves of these two SFXTs during the bright flare look similar to those
observed during recent flares from other two SFXTs, IGRJ11215-5952 and
IGRJ16479-4514, reinforcing the connection among the members of this class of
X-ray sources.
