Abstract:
We, at the Institute of Astrophysics, conducted ten experiments from two places namely Neem Ka Thana in Rajasthan and Kalpi in Uttar Pradesh. The experiments involved high spatial and spectral resolution spectroscopy to determine the temperature and velocity structure in the corona; high temporal resolution photometry to detect intensity oscillations in the corona; narrow-band photometry in three emission lines to determine the differences in 'closed' and 'open' field structure, in terms of density, temperature and turbulence, if any; photometry at near infrared (1 micron) wavelength to detect dust ring, if any; around the sun. Broad-band photometry and polarisation measurements and photometry in H-alpha line to detect cool regions in the hot ambient coronal plasma. It was for the first time successful efforts were made to photograph the solar corona using IAF planes, and students and amateur astronomers coordinated to photograph the solar corona from many different places along the length of totality path to study the gross dynamics of coronal structures. Efforts were also made to measure the solar diameter by IUCAA scientists. Many foreign teams conducted their own experiments from Neem Ka Thana, Mukandgarh Fort, Dundload Castle and a place near Agra to study the dynamics and heating mechanism in the corona and detect long term or quasi-periodic variations in the solar diameter. The analysis of high frequency photometry data shows the existence of intensity oscillations in the corona. To confirm the existence of these oscillations, delineate the size of the oscillating region and to determine the changes in these oscillations with radii, we plan to develop a multi-channel photometer during the total solar eclipses of 1998 and 1999.
