A Northern Sky Survey for Steady Tera–Electron Volt Gamma‐Ray Point Sources Using the Tibet Air Shower Array

Results of a steady TeV gamma-ray point-source search using data taken from the Tibet HD ( 1997 February - 1999 September) and Tibet III ( 1999 November - 2001 October) arrays are presented. From 0 degrees to 60 degrees in declination, significant excesses from the well-known steady source Crab Nebula and the high state of the flare-type source Markarian 421 are observed. Because the levels of significance from other positions are not sufficiently high, 90% confidence level upper limits on the flux are set assuming different power-law spectra. To allow cross-checking, two independently developed analyses are used in this work.