Astronomy

Sky Watching From India’s Largest Telescope

devasthal telescope

The effort to understand the Universe in one of the very few things that lifts human life a little above the level of a farce and gives it some of the grace of tragedy.

– Steven Weinberg, Physicist

It is somewhat rare that a Chief Minister of an Indian State takes a keen interest in astronomy! That‘s what happened in Uttar Pradesh. The late Dr. Sampurnanand took the initiative to found an institute for astronomy in the holy city of Varanasi in 1954. He was ably supported by Prof. A.N. Singh, a professor of Mathematics at Lucknow University. Soon the dust and the haze of the plains led to the relocation of the institute at Manora Peak, a few kilometers south of the picturesque Nainital. It was known as the Uttar Pradesh State Observatory, situated at a height of 1951 m.

Fifty years after its founding, the Government of India decided to convert the observatory into an autonomous institute, devoted to scientific research in the frontier areas of astrophysics and atmospheric physics. The Institute was given a new name: Aryabhatta Research Institute of Observational Sciences (ARIES) as a tribute to one of the greatest astronomers of the world, who first held that the Earth goes round the Sun. The Institute’s acronym, ARIES incidentally signifies the zodiacal sign of the Sun at its two historically significant epochs separated by half a century.

The location of ARIES (now in the state of Uttarakhand, carved out of the state of Uttar Pradesh) bestows on it a unique advantage. At 79ºE longitude, it is almost in the middle of a 180 degree wide longitude band spanned by just two astronomical facilities in the Canary Island (15ºW) and Eastern Australia (155ºE). What this means is something unique. When it is day light at either end, ARIES can observe astronomical objects both in the Northern and Southern hemispheres from its latitude of about 30º North. And the observing conditions are excellent from September to June. Thus it has been possible for ARIES to make unique contributions in astronomical research that involves time-critical phenomena, notwithstanding its small size telescopes.

Astronomers the world over were delighted at the Institute’s earliest optical observations in 2001 of the after-glows of gamma ray bursts. The institute actively participated in the discovery of the rings of Uranus (in 1977) and Neptune, and of two additional rings around Saturn.

The Institute’s other contributions include many new variable stars and active galactic nuclei, besides a rare rapidly oscillatory star in the northern part of the sky. ARIES scientists observed many new features in a large number of comets, including comet Halley. The first photometric observation of stars and occultation of a star by a minor planet were also recorded. In the Sun’s photosphere and Sunspots, the Institute’s scientists observed several new molecular species predicted earlier.

The Institute has another track record: optical tracking of artificial satellites, following the dawn of the Space Age. ARIES is one of the 12 centres across the globe set up by the Smithsonian Astrophysical Observatory, USA, during the International Geophysical Year (1957-58). The first photograph of an artificial satellite was taken on 29 August 1958. Until 1976, when the work was stopped in view of the advent of better techniques of optical tracking, ARIES had taken over 45,700 photographs of satellite transits, including Apollo-11 and India’s first satellite, Aryabhata. The camera has since been converted into one for astronomical survey.

largest telescope

The 3.6 Meter wide telescope at ARIES in Nainital, Uttarakhand.

The institute started with a 25-cm refractor in 1955. Four more telescopes were installed by 1972. The diameter of the mirrors of the telescopes progressively increased: 38 cm, 52 cm, 56 cm and 104 cm. the last cited was named after Dr. Sampurnanand and had several supporting devices: a fast photometer, a spectrometer and an imaging polarimeter, beside a CCD for recording the images and data, and an optical multichannel analyzer. The spectrometer is needed for obtaining the spectra of supernova remnants, planetary nebulae and other celestial objects. The polarimeter is used to probe the interstellar medium and magnetic field structure in interstellar clouds.

ARIES has obtained precise photometric observations of over 150 chemically peculiar stars from 1997 to 2004, using its 104-cm Sampurnanand telescope. The observed objects include delta-Scuti stars that are pulsars with periods of 30 minutes to six hours. They require extensive observations to unravel their pulsation.

A study of what is known as astroseismology would throw light on the interaction of the magnetic field and pulsation under conditions more extreme than in our Sun. In 1997 a programme called the Nainital-Cape survey was initiated by ARIES in collaboration with the South African Astronomical Observatory, ISRO, and the University of Central Lancashire. Nainital has been described as an excellent site for the proposed survey. The programme seeks to apply the observational and data resolution techniques to a northern hemisphere observational site. A fast photometer was developed and fabricated for the survey. It can provide reliable and continuous data even under moderate sky conditions. The photometer functions with the 104-cm telescope.

ARIES has facilities for maintenance, including optical electronic, electrical and mechanical workshops, besides an aluminizing unit (for periodic polishing of the mirrors) and a modern computer center. ARIES would give priority to programmes that require long duration, multi-wavelength and multi-site observations with small-size optical telescopes.

The institute has an impressive research programme for the coming years. As India advances in the observation of celestial phenomena, the Institute will support the efforts, based on optical follow-up of the observations of astronomical sources detected or discovered at millimeter, radio, infrared, ultraviolet, X-ray and gamma ray wavelengths. In fact, it is mandatory to identify the source discovered in non-optical wavelengths.

One of the most significant astrophysical findings continuing from the last decade is the presence of planetary system around stars. ARIES would actively participate in the search. Today, some 330 exoplanets (extra solar planets) have been discovered by Earth-bound and space telescopes in the world.

Asia’s Largest Telescope Inaugurated at ARIES

In 2007, ARIES signed an agreement for the joint development of Asia’s largest optical telescope with a Belgian company. The telescope’s mirror has an aperture diameter of 3.6 meter and is estimated to have cost more than Rs 120 Crore to build. It was inaugurated in March 2016 by the Prime Minister in Belgium. The telescope will be now used to conduct further research on the structures of distant stars and their magnetic fields.

You can know more about the telescope specifications at the following link : http://www.aries.res.in/projects/

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