Observational evidence for black hole spin down has been found in the normalized light curves of long GRBs in the BATSE catalogue .
Over the duration T _ { 90 } of the burst , matter swept up by the central black hole is susceptible to non-axisymmetries producing gravitational radiation with a negative chirp .
A time sliced matched filtering method is introduced to capture phase-coherence on intermediate timescales , \tau , here tested by injection of templates into experimental strain noise , h _ { n } ( t ) .
For TAMA 300 , h _ { n } ( f ) \simeq 10 ^ { -21 } Hz ^ { - \frac { 1 } { 2 } } at f = 1 kHz gives a sensitivity distance for a reasonably accurate extraction of the trajectory in the time frequency domain of about D \simeq 0.07 - 0.10 Mpc for spin fown of black holes of mass M = 10 - 12 M _ { \odot } with \tau = 1 s. Extrapolation to advanced detectors implies D \simeq 35 - 50 Mpc for h _ { n } ( f ) \simeq 2 \times 10 ^ { -24 } Hz ^ { - \frac { 1 } { 2 } } around 1 kHz , which will open a new window to rigorous calorimetry on Kerr black holes .