ON THE INTENSITY THRESHOLDS OF THE NETWORK AND PLAGE REGIONS

A period of minimum solar activity in April and May 1996 was used to a nalyze full-disk Ca K spectroheliograms with the aim of deriving the i ntensity thresholds of the quiet network and the plages by applying th e so-called inflexion point method. The average network intensity thre shold is found to be influenced mainly by the seeing, whereas the aver age plage threshold shows an increasing trend from disk center towards the solar limb. Both parameters are compared with the results of othe r authors.