The field of ground-based $\gamma$-ray astronomy has made very significant advances over the last three decades with the extremely successful operations of several atmospheric Cherenkov telescopes worldwide. The advent of the imaging Cherenkov technique for indirect detection of cosmic $\gamma$ rays has immensely contributed to this field with the discovery of more than 220 $\gamma$-ray sources in the Universe. This has greatly improved our understanding of the various astrophysical processes involved in the non-thermal emission at energies above 100 GeV. In this paper, we summarize the important results achieved by the Indian $\gamma$-ray astronomers from the GeV-TeV observations using imaging Cherenkov telescopes over the last two decades. We mainly emphasize the results obtained from the observations of active galactic nuclei with the TACTIC (TeV Atmospheric Cherenkov Telescope with Imaging Camera) telescope, which has been operational since 1997 at Mount Abu, India. We also discuss the future plans of the Indian $\gamma$-ray astronomy program with special focus on the scientific objectives of the recently installed 21 m diameter MACE (Major Atmospheric Cherenkov Experiment) telescope at Hanle, India.

中文翻译：

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利用成像Cherenkov望远镜和未来之路进行印度伽马射线天文学研究20年

地基领域 $\gamma$在过去的三十年中，随着全球几台切伦科夫大气望远镜的成功运行，射线天文学取得了巨大的进步。间接探测宇宙的成像Cherenkov技术的出现。$\gamma$ 射线已经发现了220多种，为该领域做出了巨大贡献 $\gamma$宇宙中的射线源。这极大地增进了我们对能量高于100 GeV的非热发射所涉及的各种天体过程的理解。在本文中，我们总结了印度人取得的重要成果$\gamma$最近二十年来，使用成像切伦科夫望远镜通过GeV-TeV观测得到的X射线天文学家。我们主要强调从TACTIC（带成像相机的TeV大气Cherenkov望远镜）望远镜对活动银河核进行观测所获得的结果，该望远镜自1997年在印度阿布山开始运行。我们还将讨论印度的未来计划$\gamma$射线天文学计划，特别关注最近在印度汉勒安装的直径21 m的MACE（主要大气Cherenkov实验）望远镜的科学目标。