Prof. (Dr.) Dipankar Banerjee

Kodaikanal Observatory (KSO) has archived more than 100 years of solar images in three different wavelengths, namely white light, Ca K and H-alpha. These have been captured through telescopes with unchanged optics, which ensured uniformity in image quality for several cycles. While light photoheliograms since 1904, the Ca-K line spectroheliograms since 1906, H-alpha spectroheliograms since 1912 to 1998 and K-pr prominences spectroheliograms since 1912 to 1998 have been archived. Magnetograms from ground based observatories being available after 1950, this long term data from KSO can be used as a proxy for estimating magnetic activity at earlier times. In this presentation I will highlight some of the new results from the Kodaikanal archive. The Solar Ultraviolet Imaging Telescope (SUIT) is an instrument on-board Aditya-L1 mission of ISRO that will measure and monitor the solar radiation emitted in the near ultraviolet wavelength range (200–400 nm). In the last part of the presentation I will point out how SUIT will enable us to study the spectral irradiance variation and the magnetic activity on the sun.