Observation of Small Air Shower Lasted in Short Arriving Time

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1) The observations have been continued since August 17th in 1989.The total real time is 1935.7 hours and the observed event number is 31,750 up to the end of February, the frequency being 16.4 hour.2) It is confirmed that almost all the events follow Poisson distribution.3) In the observation, several events with deviations of over 3 sigma were found (we cannot give the definite number at present because of variations of the number according to changes of time bin).4) Moreover, one example in which above 10 events arrived within 0.8 sec was found. We are under studying how to give the definite conclusion for this example and the several events cited above to be extraordinary.5) We are now preparing to set an absolute time scale with accuracy less than 1 micro-second for one year operation. This is for studying any correlation of these events with astronomical sources.6) The absolute time scale is also for making coincidences of our experimental apparatus with other apparatus where are over 50 km distant from our apparatus. This may be valid for observations of ultrahigh energy air showers with energies above 10 EeV.