China Tibetannet  Construction of a "world class" observatory could start in western China within the next five years, an official with the Chinese Academy of Sciences (CAS) said on Tuesday.
   Two sites for the observatory are currently under consideration - Karasu, on the Pamir Plateau in Xinjiang, and Oma, in southwest Tibet - but the search for the exact site is expected to take at least three years, according to Xue Suijian, director of Science and Technology section of National Astronomical Observatories under CAS.
   "When the location is chosen, we hope to set up the world's most advanced optical science facilities through international cooperation," Xue said.
   "The current observatories in China do not meet the country's research needs in the field of astronomy," he said.
    He said scientists had installed some observatory equipment at the two sites to examine whether or not the location was up to standard for a "world class" observatory.