Variability of radiation from the Crab Nebula

We consider variations of the radiation from the Crab Nebula in two energy ranges: X-rays (2–10 keV) and very-high-energy (>1 TeV) gamma rays. We demonstrate the presence of sine-shaped quasi-periodic variations in the X-ray range, with the period P = 862 d. A positive correlation was detected between variations of X-rays and gamma rays (the HEGRA data) with time.