HAGAR is a system of seven Non-imaging Atmospheric Cherenkov Telescopes located at Hanle in the Ladakh region of the Indian Himalayas at an altitude of 4270 meters amsl. Since 2008, we have observed the Crab Nebula to assess the performance of the HAGAR telescopes. We describe the analysis technique for the estimation of γ-ray signal amidst cosmic ray background. The consolidated results spanning nine years of the Crab nebula observations show long term performance of the HAGAR telescopes. Based on about 219 hours of data, we report the detection of γ-rays from the Crab Nebula at a significance level of about 20σ, corresponding to a time averaged flux of (1.64±0.09) × 10− 10 photons cm− 2 sec− 1 above 230 GeV. Also, we perform a detailed study of possible systematic effects in our analysis method on data taken with the HAGAR telescopes.

中文翻译：

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使用HAGAR望远镜阵列对蟹状星云的VHE伽马射线观测

HAGAR 是一个由七个非成像大气切伦科夫望远镜组成的系统，位于印度喜马拉雅山拉达克地区的 Hanle，海拔 4270 米 amsl。自 2008 年以来，我们观察蟹状星云以评估 HAGAR 望远镜的性能。我们描述了在宇宙射线背景中估计 γ 射线信号的分析技术。跨越九年蟹状星云观测的综合结果显示了 HAGAR 望远镜的长期性能。基于大约 219 小时的数据，我们报告了在大约 20σ 的显着性水平上检测到来自蟹状星云的 γ 射线，对应于 (1.64±0.09) × 10− 10 光子 cm− 2 sec− 的时间平均通量1 高于 230 GeV。此外，我们对使用 HAGAR 望远镜采集的数据的分析方法中可能的系统影响进行了详细研究。