Giant telescope begun.

Construction of what will be the world's largest telescope began with a ground-breaking ceremony Sept. 12 on the summit of Mauna Kea on the island of Hawaii. The instrument, to be known as the W.M. Keck Telescope, will have a mirror 10 meters in diameter. The world's largest telescope now is a 6-meter mirror in the Soviet Union.

The Keck telescope will hve a radically new design. Its mirror will be built of smaller segments, each with independent support and positioning control. (Manufacture of a monolithic 10-meter mirror is considered impractical.) The design is largely by astronomers of the University of California. The California Association for Research in Astronomy, which represents the University of California and California Institute of Technology, will build the new telescope. The cost of construction, about $87 million, will be supplied by Caltech in Pasadena, mainly from a grant by the Keck Foundation of Los Angeles. The 13,000-foot Mauna Kea offers some of the best astronomical seeing in the world. Housing several other telescopes, its summit is fast becoming an astronomer's acropolis.