The Kodaikanal observatory have been acquiring photoheliograms of the Sun, at the 3933.67 Å, since 1904 on daily basis using a 15 cm aperture telescope. Details on the instrument, calibration etc. are described in Priyal et al 2014bSolar Physics, 289, 137
Butterfly Diagram from Kodaikanal Plage data
Click here for a 3-D view of the butterfly diagram
This data has also been used by Mandal et al 2016 to establish the one-to-one connection between the sunspot and the plages.
Observation Statistics of Ca-K (1904-2011)