A Study of Uhe Cosmic Gamma Rays at Mt. Chacaltaya - Gamma Ray Sources in SN 1987A and the Southern Ssy -

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The Bolivian Air Shower Joint Experiment group has operated two air shower arrays in order to search for point and diffuse gamma-ray sources at Mt. Chacaltaya (5200m, 68.1^oW, 16.3^oS) in Bolivia. The purpose of the study is to make clear the problem on Cosmic Ray Origin.After three years observations, the observed results are as follows :1. UHE gamma-ray emission from X-ray eclipsing binaries (Vela X-1, Cen X-3, X1822-371), Vela pulsar, a radio galaxy (Cen A), a flaring X-ray source (SS433) and the center of Galaxy are examined by comparing the amount of onーsource low muon events with that of background cosmic rays estimated from off-source low muon events. The results at present show no significant evidence of UHE gamma-ray emission from the above mentioned objects. The 95% C. L. upper limits of the emission are obtained.2. Observation for UHE gamma-ray emission from notable SN1987A has been carried out since January 1988. The DC excess for daily and weekly variation was analyzed. There is no significant evidence concerning the arrival of UHE gamma-rays from SN1987A. No information is also presented any group in Australia, New Zealand, the Republic of South Africa and the South Pole. The upper limit on the flux of gamma-rays with energies above 100 TeV is estimated as being 2.4 x 10^<-13>cm^<-2>s^<-1> (95% C. L.).3. Diffuse gamma-rays with energies above 100 TeV is analyzed using selected shower with low content of muons. Our interesting region is that of 180^ﾟ - 210^ﾟ in right ascension (R. A.) and 0^ﾟ - -40^ﾟ in declination (delta) from the report in 1985. However, it wasn't found the excess in a such region. In place of this region, new one of 135^ﾟ- 150^ﾟ in R. A. and -20^ﾟ --40^ﾟ in delta presents 4.6sigma (sigma, standard deviation) of the excess. Li-Ma test for small number events, however, shows 3.2sigma. So, it seems statistically no significant.