CGRO/EGRET observations of Centaurus X-3

We review evidence for the first detection of GeV gamma-rays from the massive x-ray binary system Centaurus X-3. The CGRO/EGRET detection of an outburst of gamma-ray emission from the direction of Cen X-3 occurred during an interval of rapid spindown by the x-ray pulsar. Our phase analysis of photon arrival times, employing the contemporaneous x-ray pulse observations by CGRO/BATSE, indicates modulation of the gamma-ray emission at the pulsar spin frequency with a significance level higher than 99.5%. Straightforward interpretation of the observations suggests that accreting pulsars may constitute a class of highly variable GeV gamma-ray emission.