About the PRL Mount Abu Observatory at Gurushikhar, Mount Abu

The idea of setting up an optical observatory and initiating the infrared and optical astronomy programme was put forth by PRL during the 1970s. After a suitable astronomical site survey of several locations, Gurushikhar, the highest peak of Aravali range in Mt Abu, Rajasthan (India), was found most appropriate due to its low water vapour, more than 220 observable nights with reasonably good seeing and the site's vicinity to PRL, Ahmedabad (240 kms). The first Telescope that came up at the sight is the 1.2m Telescope.

The construction work for the 1.2m Telescope Observatory Building started around the year 1986. The responsibility of developing the site, including the construction of the access road, telescope building and other facilities, telescope mount and dome, etc., was given to ISRO. The whole observatory was designed and developed indigenously. The design of telescope drives, mount and other support systems, including telescope control, was taken up by the SHAR Centre which also supervised the fabrication work at Chennai. The Telescope 1.2m primary mirror blank came from University of Arizona, US (It was donated by Late Prof. Tom Gehrels), and the Mirror blank was polished in United Kingdom. All the back-end instruments, one of the most important components of the astronomical observations, were developed in parallel with the setting up of the observatory. It may be worth noting that some of those initial instruments are still functioning and competing with new generation instruments. The “first Light” image of star alpha Arietis was acquired with the 1.2 m telescope on November 19, 1994 establishing excellent quality of its optics. The observatory started regular operation immediately with the lunar occultation study of IRC-10557 (v Aquarii) on December 7, 1994. Over the years, it has catered to the observational requirements of the scientific programs of the Astronomy and Astrophysics faculty.

The research programs currently cover a wide range of objects and events, such as studies of solar system objects, search and characteristics of exoplanets, topics in stellar astrophysics like star formation, stellar structure and evolution, Novae and binary systems, supernovae, and starburst and active galactic nuclei. The techniques used are imaging photometry, spectroscopy and polarimetry.

Subsequently due to demand of continous photometric observations of transiant astrophysical phenomena like Novae, GRBs, Cometary Studies etc., it was decided to have a small automated 50cm Telescope to observe such sources using CCDs. Hence ATVS 50cm was installed around 2011. Further more to do follow-up transit observations of exoplanets, it was decided to have a 43cm Telescope with a large field of view. The 43cm Telescope became active since January 2019.

In early 2014, PRL Astrophysicists recognized the need for a larger aperture telescope specifically tailored to PRL’s dedicated exoplanetary science and target of opportunities (TOO) programs. The decision to initiate a 2.5m telescope project at Gurushikhar was made and subsequently in February 2015, a contract was signed with Advanced Mechanical and Optical Systems (AMOS) in Liège, Belgium. The kick-off meeting took place in mid-July 2016, leading to the Factory Acceptance Test (FAT) in September 2020 and the Site Acceptance Test (SAT) concluding by October 2022.

The PRL 2.5m telescope is a highly advanced telescope in India, featuring the Ritchey-Chrétien optical configuration with primary mirror active optics, tip-tilt on side-port, and wavefront correction sensors. Along with the telescope, its first light instruments, the Faint Object Camera (FOC) and PARAS-2, were also integrated and attached to it in June 2022. The FOC, a 10x10 sq. arcminute FOV CCD Imager with SDSS Filter sets, was designed primarily for detailed scientific observations and study of transient astrophysical phenomena. PARAS-2 is an advanced version of PARAS designed to detect and study exoplanets. It operates at a resolution of 107,000 under the stabilized environment of temperature and pressure, at 24 ± 0.001◦C and 0.005 ± 0.0005 mbar, respectively.

PRL is also developing additional backend instruments for the 2.5m telescope, such as Near Infrared Spectrograph and Polarimeter (NISP), Low- Resolution Spectrograph (LRS), and an echelle spectro-polarimeter (MFOSC-EP & its proto-type) which will see the first light in the upcoming 1-2 years for various astrophysical studies.

All telescopes are operated by the Physical Research Laboratory and are fully funded by the Department of Space, Govt. of India.

ADDRESS

Mount Abu Observatory, Near Gurushikhar, Mt. Abu-307501, (Rajasthan) India
Coordinates : 24°39′17.34″N 72°46′45.18″E
Altitude : 1,680 m (5,510 ft)

Mount Abu Observatory Base Office, Observer Transit House, Residential Campus:
Hillview, Gora Chapara, Mt. Abu 307501, (Rajasthan), India
Phones: +91-02974-235229 Fax No: +91-02974-238276


For visit requests: [email protected]