Jagdev Singh

NameJagdev Singh
AffiliationIndian Institute of Astrophysics, Bengaluru
TitleKodaikanal Synoptic Programs – Historic and Modern
AuthorsJagdev Singh
AbstractThe synoptic observations of the sun at Kodaikanal observatory were started in the year 1904 by taking the broad-band images of the sun on daily basis and are being taken with the same 15-cm telescope. Afterwards spectro-heliograms in Ca-K and H-alpha were taken on daily basis since 1905 and 1912, respectively. The images of off-limb prominences were also obtained in Ca-K or H-alpha lines and continued till 2007. As the photographic films became unavailable, Ca-K line filter-grams were obtained beginning in 1998 and H-alpha filter-grams in 2014 using newly developed Twin-telescope and H-alpha telescopes. The monitoring of Ca-K line profiles of Sun as a star began in 1969 and as a function of latitude in 1986 at Solar Tower Telescope. A new methodology of Equal Contrast Technique (ECT) has been developed to analyse the Ca-K line historic photographic images. This procedure enables to correlate the sunspot and Ca-K line data on day-to-day basis, for the first time. This methodology will also help to combine the Ca-K data from different instruments at different observatories to generate a long time series with minimum gaps.