We report on the spectral ( pulse averaged ) and timing analysis of the \sim 20 ksec observation of the X–ray binary pulsar Vela X–1 performed during the BeppoSAX Science Verification Phase .
The source was observed in two different intensity states : the low state is probably due to an erratic intensity dip and shows a decrease of a factor \sim 2 in intensity , and a factor 10 in N _ { H } .
We have not been able to fit the 2–100 keV continuum spectrum with the standard ( for an X–ray pulsar ) power law modified by a high energy cutoff because of the flattening of the spectrum in \sim 10 –30 keV .
The timing analysis confirms previous results : the pulse profile changes from a five-peak structure for energies less than 15 keV , to a simpler two-peak shape at higher energies .
The Fourier analysis shows a very complex harmonic component : up to 23 harmonics are clearly visible in the power spectrum , with a dominant first harmonic for low energy data , and a second one as the more prominent for energies greater than 15 keV .
The aperiodic component in the Vela X–1 power spectrum presents a knee at about 1 Hz .
The pulse period , corrected for binary motion , is 283.206 \pm 0.001 sec .