The faint 2005 hard state outburst of Aquila X-1 seen by INTEGRAL and   RXTE
  We report on the spectral analysis of RXTE and INTEGRAL data of the 2005 April outburst of the transient Atoll source Aql X-1. Although this outburst is one of the faintest ever detected for this source in the soft X-rays (RXTE/ASM), one of our INTEGRAL observations, taken close to the soft X-ray peak, shows that the source flux was quite high, with a 20-200 keV flux of 2.05 x 10^-9 erg cm^-2 s^-1. On this occasion we detect the source up to 150 keV for the first time. We compare and discuss the similarity of the source behavior with that of black hole transients especially XTE J1550-564. 
Jerome Rodriguez, Simon E. Shaw, Stephane Corbel