Hard xray data from the RXTE observatory ( HEXTE energy range 15 to 240 keV ) have been analyzed to obtain a phase coherent timing solution for the Crab pulsar glitch of 15 July 2000 .
The results are : ( 1 ) step change in the rotation frequency \nu _ { 0 } of the Crab pulsar at the epoch of the glitch is \Delta \nu _ { 0 } = ( 30 \pm 3 ) \times 10 ^ { -9 } \times \nu _ { 0 } , ( 2 ) step change in its time derivative is \Delta \dot { \nu } _ { 0 } = ( 4.8 \pm 0.6 ) \times 10 ^ { -3 } \times \dot { \nu } _ { 0 } , and ( 3 ) the time scale of decay of the the step change is \tau _ { d } = 4.7 \pm 0.5 days .
The first two results are consistent with those obtained at radio frequencies by the Jodrell Bank observatory .
The last result has not been quoted in the literature , but could be an underestimate due to lack of observations very close to the glitch epoch .
By comparing with the monthly timing ephemeris published by the Jodrell group for the Crab pulsar , the time delay between the main peaks of the hard xray and radio pulse profiles is estimated to be +411 \pm 167 \mu sec .
Although this number is not very significant , it is consistent with the number derived for the 2 to 16 keV energy range , using the PCA instrument of RXTE .
The separation between the two peaks of the integrated pulse profile of the Crab pulsar , and the ratio of their intensities , both are statistically similar before and after the glitch .
The dead time corrected integrated photon flux within the integrated pulse profile appears to decrease after the glitch , although this is not a statistically strong result .
This work achieves what can be considered to be almost absolute timing analysis of the Crab pulsar hard xray data .