Indian Scientists Develop Low-Cost Optical Spectrograph For Observation Of Extremely Faint Celestial Objects

Indian Scientists have indigenously designed and developed a low-cost optical spectrograph that can locate sources of faint light from distant quasars and galaxies in a very young universe, regions around supermassive black-holes around the galaxies, and cosmic explosions.

Such spectroscopes were so far imported from abroad and involved high costs.

The ‘Made in India’ optical spectrograph has been named as Aries-Devasthal Faint Object Spectrograph and Camera (ADFOSC). It is indigenously designed and developed by Aryabhatta Research Institute of observational sciences (ARIES), Nainital, which is an autonomous institute of Department of Science and Technology (DST).

The spectrograph is about 2.5 times less costly compared to the imported ones and can locate sources of light with a photon-rate as low as about 1 photon per second, the Ministry of Science and Technology said in a statement on Wednesday (3 March).

The spectroscope, which is the largest of its kind among the existing astronomical spectrographs in the country, has been successfully commissioned on the 3.6-m Devasthal Optical Telescope (DOT), the largest in the country and in Asia, near Nainital in Uttarakhand, the ministry said.

This instrument, a backbone of the 3.6-m DOT for observations of extremely faint celestial sources, uses a complex arrangement of several lenses made of special glasses, polished to better than 5-nanometer smoothness to produce sharp images of the celestial sky.

Photons coming from distant celestial sources, collected by the telescope, are sorted into different colors by the spectrograph and are finally converted into electronic recordable signals using an in-house developed Charge-Coupled Device (CCD) camera cooled to an extremely low temperature of -120 degree celsius. The total cost of this instrument is nearly Rs 4 Crore, the ministry said.

Dr Amitesh Omar, a scientist at ARIES, led this project with a technical and scientific team, which together researched and developed various optical, mechanical, and electronics subsystems of the spectrograph and camera.

The spectrograph is presently being used by astronomers from India and abroad to study distant quasars and galaxies in a very young universe, regions around supermassive black-holes around the galaxies, cosmic explosions like supernovae and highly energetic Gamma-ray bursts, young and massive stars, and faint dwarf galaxies.

“The indigenous efforts to build complex instruments like ADFOSC in India is an important step to become ‘Aatmanirbhar’ in the field of astronomy & astrophysics,” said Professor Dipankar Banerjee, Director, ARIES.

Expertise from various national institutes, organizations, including the Indian Space Research Organization (ISRO) and some micro-small-medium-enterprises, were involved to review and build parts of the instrument serving as an example of effective collaboration, the ministry said.

With this expertise, ARIES now plans to commission more complex instruments such as spectro-polarimeter and high spectral resolution spectrograph on the 3.6-m Devasthal telescope in the near future, it added.