Search For Rapid X-ray Variability from the Black-Hole Candidate GRO   J1655-40
  We have examined fifteen days of CGRO/BATSE data, obtained during the first outburst of the black-hole candidate source GRO J1655-40, to search for rapid variability of its X-ray flux. We find no evidence for significant variability of GRO J1655-40 during our observations, with a 2 sigma upper limit to the fractional r.m.s. amplitude in the frequency range 0.03-0.488 Hz of 6.6%. We cannot, on the basis of our observations, determine the source state (low, high, or very-high state) of GRO J1655-40. 
D.J. Crary, C. Kouveliotou, J. van Paradijs, F. van der Hooft, M. van   der Klis, B.C. Rubin, D.M. Scott, M.H. Finger, and B...