Pointing of HAGAR telescope mirrors

Gothe, K. S. ; Prabhu, T. P. ; Vishwanath, P. R. ; Acharya, B. S. ; Srinivasan, R. ; Chitnis, V. R. ; Kamath, P. U. ; Srinivasulu, G. ; Saleem, F. ; Kemkar, P. M. M. ; Mahesh, P. K. ; Gabriel, F. ; Manoharan, J. ; Dorji, N. ; Dorjai, T. ; Angchuk, D. ; D’souza, A. I. ; Duhan, S. K. ; Nagesh, B. K. ; Rao, S. K. ; Sharma, S. K. ; Singh, B. B. ; Sudersanan, P. V. ; Thsering, M. Tashi ; Upadhya, S. S. ; Anupama, G. C. ; Britto, R. J. ; Cowsik, R. ; Saha, L. ; Shukla, A. (2013) Pointing of HAGAR telescope mirrors Experimental Astronomy, 35 (3). pp. 489-506. ISSN 0922-6435

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Official URL: http://link.springer.com/article/10.1007/s10686-01...

Related URL: http://dx.doi.org/10.1007/s10686-012-9319-9


An array of seven atmospheric Cherenkov telescopes was commissioned at a high altitude site in Hanle in the Ladakh region of the Himalayas. The array called HAGAR has been designed to observe celestial γ-rays of energy >100 GeV. Each telescope is altitude-azimuth mounted and carries seven parabolic mirrors whose optic axes are co-aligned with the telescope axis. The telescopes point and track a celestial source using a PC-based drive control system. Two important issues in positioning of each HAGAR telescope are pointing accuracy of telescope axis and co-alignment of mirrors’ optic axes with the telescope axis. We have adopted a three pronged strategy to address these issues, namely use of pointing models to improve pointing accuracy of the telescopes, RA-DEC scan technique to measure the pointing offsets of the mirrors and mechanical fine-tuning of off-axis mirrors by sighting a distant stationary light source. This paper discusses our efforts in this regard as well as the current status of pointing and monitoring of HAGAR telescopes.

Item Type:Article
Source:Copyright of this article belongs to Springer Verlag.
Keywords:Telescope Pointing; γ-ray Astronomy; Pointing Model; Atmospheric Cherenkov Telescopes
ID Code:100874
Deposited On:10 Dec 2016 12:11
Last Modified:10 Dec 2016 12:11

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