Scientists have indigenously designed and developed a low-cost optical spectrograph that can locate sources of faint light from distant quasars and galaxies. It can also detect regions around supermassive black holes around the galaxies, and cosmic explosions, the Department of Science and Technology said. Till now, these spectrographs were imported to India.
The optical spectrograph named as Aries-Devasthal Faint Object Spectrograph & Camera (ADFOSC) has been designed and developed by Aryabhatta Research Institute of Observational Sciences (ARIES), Nainital. It's about two-and-a-half times less costlier compared to the imported ones and can locate sources of light with a photon-rate as low as about one photon per second. The total cost of this instrument is around ₹4 crore.
The largest of its kind among the existing astronomical spectrographs in the country, it has been successfully commissioned on the 3.6-m Devasthal Optical Telescope (DOT). The optical telescope, located near Nainital in Uttarakhand, is the largest in not only India but also Asia.
The spectrograph, 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 that are polished to better than five nanometer smoothness to produce sharp images of the celestial sky.
Photons coming from distant celestial sources, collected by the telescope, are sorted into different colours 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 minus 120 degrees Celsius.
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 and astrophysics,” said Dipankar Banerjee, director, ARIES.
Expertise from various national institutes, organisations including the Indian Space Research Organisation (ISRO) and some micro-small-medium (MSME) enterprises, were involved to review and build parts of the instrument serving as an example of effective collaboration, the DST added.
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.