  The black hole candidate 1E 1740.7-2942 is one of the strongest hard X-ray
sources in the Galactic Center region. No counterparts in longer wavelengths
have been identified for this object yet. The presence of characteristic timing
signatures in the flux history of X-ray sources has been shown to be an
important diagnostic tool for the properties of these systems. Using
simultaneous data from NASA's Swift and ESA's INTEGRAL missions, we have found
two periodic signatures at 12.61 $\pm$ 0.06 days and 171.1 $\pm$ 3.0 days in
long-term hard X-ray light curves of 1E 1740.7-2942. We interpret those as the
orbital and superorbital periods of the object, respectively. The reported
orbital period is in good agreement with previous studies of 1E 1740.7-2942
using NASA's RXTE data. We present here the first firm evidence of a
superorbital period for 1E 1740.7-2942, which has important implications for
the nature of the binary system.
