Astrophysical Journal 624,2 (2005) 638-655;
The Whipple Observatory 10 m γ-ray telescope has been used to survey the error boxes of EGRET unidentified sources in an attempt to find counterparts at energies of 350 GeV and above. Twenty-one unidentified sources detected by EGRET (more than 10% of the total number) have been included in this survey. In no case is a statistically significant signal found in the EGRET error box, which implies that, at least for this sample, the γ-ray spectra of these sources steepen between 100 MeV and 350 GeV. For each EGRET source location, we list candidate associations and derive upper limits on the integral γ-ray flux above 350 GeV.
galaxies : jets;; gamma rays : observations;; surveys;; gamma-ray sources;; source 3eg j2227+6122;; x-ray;; galactic plane;; ls i+61-degrees-303;; supernova-remnants;; galaxy clusters;; sax j0635+0533;; tev energies;; error box
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