news AMOS delivered a 2.5m telescope to Physical Research Laboratory, India

At the instigation of Prof. Abhijit Chakraborty, the Physical Research Laboratory (PRL), a Unit of Department of Space in India, decided to equip their observatory with a new large telescope, much more powerful and efficient telescope than the 1.2 m telescope installed some decades ago.

AMOS designed and manufactured this large 2.5 m telescope based on the parameters defined by PRL in the telescope tender. AMOS recently installed it at the Mount Abu observatory site at Gurushikar in Rajasthan, India. The site, located 1700 m above the see level, is one of the best in India for astronomical observations in the visible and infrared wavelengths.

The PRL research in astronomy and astrophysics mainly focuses on galactic and extragalactic cosmic phenomena, such as star formation, stellar evolution, interstellar medium, binary stars, pulsars, active galactic nuclei, as well as exoplanets tracking and the study of the evolution of solar system bodies. The telescope will be operated mostly in combination with the optical fibre-fed high-resolution cross-dispersed echelle spectrograph (PARAS-2) and other back-end instruments developed by PRL.

The telescope design is based on a Ritchey-Chrétien Cassegrain configuration with a focal length of 20 m. The ultimate image quality is obtained thanks to the active optic system where the 2.5 m primary mirror shape is controlled by means of 42 actuators and the position of the secondary by means of a hexapod. A built-in wavefront sensor and a camera provide feedback information, respectively, for the active optic and tracking closed loop. The telescope can host at Cassegrain focus one main instrument and two side instruments that are selected automatically. It is robust enough to embark instruments of 400 kg on the main port and 150 kg on the two side ports.

Major components such as the 2.5 m primary mirror and the mount structural parts were manufactured at AMOS. The assembly of the telescope was performed in the large assembly hall in Liège, Belgium. All the components were integrated, followed by the alignment of the optics, the tuning of the axes, the functional tests and finally the first performance tests on sky in September 2020 in Liège.

The Factory Acceptance was celebrated on 16 October 2020, in the presence of Mr Borsus, Walloon Minister of the Economy and Vice-President of the Walloon Region, and His Excellence Santosh Jah, Ambassador of India in Belgium, the Director of PRL, Prof. Anil Bhardwaj and the Director of ARIES Prof. Dipankar Banerjee.

The telescope was shipped to India end of 2020 and arrived on-site beginning of 2021. However, the pandemic situation in the world prevented any installation at that time. Most of the crates were stored in the observatory building and a good collaboration between AMOS and PRL allowed to protect the remaining containers well enough to support the monsoon season. Installation resumed end 2021 and was mostly completed before the monsoon 2022.

The final acceptance tests took place in October 2022 in presence of a review board of 25 scientific and engineers from the Indian astronomical community. The outstanding performances of the telescope were demonstrated: image quality better than 70 nm RMS and tracking accuracy better than 0.15 arcsec. The results from the tests were fully compliant with the requirement specifications.

PRL already equipped the telescope with its PARAS-2 instrument, a cutting-edge radial velocity spectrometer. Despite the instrument being still in commissioning, some scientific observations have already been performed successfully.

Prof. TGK Murty, Ex-Director of ISRO, and original contract signatory for the 2.5 m telescope of PRL, expressed its “… deepest appreciation for wonderful work you carried in tandem (with PRL), with … the unflinching support received from Dr Kiran Kumar and Prof Anil Bhardwaj, respectively, Chairman of PRL Governing Council and PRL Director. “

The PRL director Prof. Anil Bhardwaj expressed his great satisfaction on the completion of the 2.5 m Telescope and conveyed his “BIG THANK YOU” to team AMOS.

This is the fourth telescope that AMOS installed in India. AMOS is proud of the trust that Indian institutes have in AMOS telescopes.

AMOS has been present in India for more than 20 years, delivering telescopes, optics, space hardware and test systems to various customers in India. “AMOS know-how and expertise is renowned in India. Our partners know that when they purchase a telescope or an instrument from AMOS, they get an unprecedented performance for their budget. The successful completion of this PRL project is a new testimony of AMOS’ capability to deliver world-class telescopes around the world. The pandemic added significant difficulties to the project execution. I would like to thank the various people who worked on this project, both in AMOS and in PRL, in order to produce this world-class telescope.” said Xavier Verians, Director Business Development of AMOS.

Press Release – FR