V0332+53

L. Stella and N. E. White, European Space Agency, report that a more detailed analysis of the EXOSAT observations of V0332+53 on Nov. 21 and 22 (IAUC 3893) has revealed a coherent 4.4-s modulation of the x-ray flux. The pulse profile is variable but on the average is a double-sine-wave pulse with a peak-to-peak amplitude of 15 percent. This modulation was also present in an additional observation on Nov. 26. The period is decreasing with P/P-dot = 200 +/- 50 yr from a value of 4.37534 +/- 0.00004 s on Nov. 21.22 UT. This rate of decrease is similar to that seen from other x-ray pulsars. The variance associated with the modulation is < 10 percent of that caused by the stochastic flickering previously reported.