  AX J1845.0-0433 is a transient high-mass X-ray binary discovered by ASCA. The
source displays bright and short flares observed recently with INTEGRAL. The
transient behaviour and the bright and short flares are studied in order to
understand the accretion mechanisms and the nature of the source. Public
INTEGRAL data and a pointed XMM-Newton observation are used to study in details
the flaring and quiescent phases.
  AX J1845.0-0433 is a persistent X-ray binary with a O9.5I supergiant
companion emitting at a low 0.2-100 keV luminosity of ~1e35 erg/s with seldom
flares reaching luminosities of 1e36 erg/s. The most-accurate X-ray position is
R.A. (2000) =18h45m01s.4 and Dec. = -04deg33'57''.7 (uncertainty 2'').
Variability factors of 50 are observed on time scale as short as hundreds of
seconds. The broad-band high-energy spectrum is typical of wind-fed accreting
pulsars with an intrinsic absorption of NH=(2.6+/-0.2)e22 cm-2, a hard
continuum of Gamma=(0.7-0.9)+/-0.1 and a high-energy cutoff at Ecut=16+/-3 keV.
An excess at low energies is also observed fitted with a black body with a
temperature of kT=0.18+/-0.05 keV. Optically-thin and highly-ionised iron (Fe
XVIII-XIX) located near the supergiant star is detected during the quiescence
phase. The spectral shape of the X-ray continuum is constant. The flare
characteristics in contrast to the persistent quiescent emission suggest that
clumps of mass M~1e22 g are formed within the stellar wind of the supergiant
companion.
