摘要
The Beijng Huairou extensive air shower(EAS)array has been operating since March 1988.Using data observed during the period from April 1991 through January 1993,a burst of 12 EAS events were observed within 2-minute interval beginning at 4:41′54〃ante meridiem on December 301991 universal time,while only 2 EAS events on average would have been expected during such time interval.
