  Since its outburst in 1997 GS 135-64 stayed in quiescence. In June 2015
renewed activity of GS 1354-64 was observed. Based on our analysis of energy
spectra and timing properties obtained from Swift/XRT monitoring data we found
that GS 1354-64 stayed in the hard state during the entire outburst. Such a
hard state only (or "failed" outburst) has also been observed in 1997. In
addition, we analysed an XMM-Newton observation taken on August 6th. We
compared variability on long and short time scales using covariance ratio and
found that the ratio showed a decrease towards lower energies instead of the
increase that has been found in other black hole X-ray binaries. There are now
two sources (H 1743-322 and GS 1354-64) that do not show an increase towards
lower energies in their covariance ratio. Both sources have been observed
during "failed" outbursts and showed photon indices much harder than what is
usually observed in black hole X-ray binaries.
