Lecture on New Advances In Optical Astronomy

On Saturday, 4th August there was a lecture arranged by the Nehru science centre, Mumbai. Nehru Science centre is going to conduct a lecture series “Vistas In Astronomy” and Saturday’s lecture was the inaugural lecture. The topic was “Advancement in Optical Astronomy”. Prof. Ram Sagar, Director of Aryabhatta Research Institute
of observational SciencES (ARIES) was the honorable speaker for the lecture. The ARIES is situated in the high altitude Manora peak of Nainital. ARIES has 4 giant telescopes and it is building a 3.6 m huge telescope in the Devasthal near Nainital.

In his speech Prof. Ram Sagar briefly discussed different kinds of telescopes (detectors) used for the different wavelengths of light. Then he gave the statistics differentiating the abilities of human eye and telescopes and discussed the need of having bigger aperture for light gathering. He also discussed the difference in ground based telescope and a satellite telescope and mensioned the new techniques implemented to overcome the difficulties like air turbulence. He described the new technique of auto correcting the curvature of large diameter telescopes used with comparatively less thickness. This technique has decreased the cost of building the large diameter telescopes. Then he described the advantages of using photographic plate over human eye and the charge coupled devices (CCD’s) over the photographic plates.

After he finished his lecture I asked him the first question: “Why the interferometry is not yet been used effectively with optical telescopes?” On this question he gave the answer as, “The incoherence in the coming beam of light is the main problem implementing the interferometry in the optical region. In radio interferometry we are working on the specific wavelength and hence the problem does not occur. But in case of optical observations we are dealing with a band of spectrum and hence we have to take into consideration the incoherence.”

The overall lecture was very good and informative. The response to the lecture was also very good. From Khagol Mandal, I, Anup, Nilesh, Sameer, Jay, Vikrant, Anshulee, Akshaya, Vineeta and Juie attended the lecture.