Search for point sources of ultrahigh energyγrays in the southern sky

A search for point sources of $\gamma$ rays with energies ≳ 100 TeV which has been made by the JANZOS Collaboration using an array of plastic scintillators located at Black Birch mountain in New Zealand is reported. The physical characteristics of the array are described, and also the techniques which have been used to analyze the data. Measurements of the angular resolution of the array using the Moon and/or Sun shadowing technique, and also a comparison test with the JANZOS array of Čerenkov mirrors, are reported. About 80 million events were observed in the period October 1987 to January 1992. Upper limits on the average $\gamma$-ray fluxes at energies ≳ 100 TeV from SN 1987A, Vela Pulsar, Vela X-1, LMC X-4, Sco X-1, Cen X-3, SMC X-1, Galactic Center, Cen A, 4U1145-619, 2A1822-371, and PSR1706-44 in this period are reported. The limits are compared with previous measurements which were made at various energies by several groups. Monthly measurements for the flux from SN1987A are also reported, and a search of the southern sky for unknown sources of ultrahigh energy $\gamma$ rays is described. Some plans for future observations are given.