Digitized Archival Data: 1904 onwards

The Kodaikanal observatory has been obtaining solar images since 1904 in broad band white light, narrow band Ca-K 393.37 nm and Hα 656.3 nm wavelengths. Many of these observations are still continuing. The historical data which were on photographic plates has been digitized. The first level calibration of the Ca-K, white light and Hα images have been completed and the data is now available through this portal. Final calibrated images and the data will be posted on this site in near future. The data availability and statistics can be accessed through our interactive data visualization tool. You can also search for data using specific constraints using using our archive search tool.

The Filters

White-light (since 1904)
Ca-K (since 1907)
Hα (since 1912)

Description of the different data levels:

Level 0a: Raw images with three qualities (good, normal and bad). Dark is subtracted during Digitisation.
Level 1a: Flat, bias corrected, Disc centred, rotation corrected with non-uniform radii with three qualities (good, normal and bad)
Level 1b (LDC): Limb darkening corrected disc centred image with uniform radii.