Method of digitization and analysis of K chromospheric filtergrams in a solar rotation study

The data analysis procedure, relative to a study of solar rotation at cromospheric level, is described. Daily cromospheric filtergrams in the K line of Ca II, covering the interval 1972-1973, are digitized. Then the digitized data, expressed as functions of time and heliolatitude, are analyzed to evaluate the chromospheric synodic rotation period. This work has been performed with the use of the SADAF flying-spot photometer controlled by a PDP/8/I computer, at the IEI of Pisa.