The 1000 ft. (305 m) diameter Arecibo radio telescope is the largest single-dish telescope in the world. The spherical dish is too large to move. Pointing is accomplished by the rotation of the earth. A 40-degree wide band of the sky parallel to the celestial equator is visible to the telescope. Although the telescope is not steerable, some directionality is obtained by moving the feed antenna (upgraded in 1996). The immense size and accurate configuration of the dish allows extremely faint signals to be detected. For this reason, it has been used extensively in SETI investigations and in the first attempt at CETI. It also featured in the film Contact. Use of the Arecibo Observatory is available on an equal, competitive basis to all scientists from throughout the world. Observing time is granted on the basis of the most promising research as ascertained by a panel of independent referees who review the proposals sent to the Observatory by interested scientists. Every year about 200 scientists visit the Observatory facilities to pursue their research project, and numerous students perform observations that lead to their master and doctoral dissertations.