Search for variable sources using the data of Cold surveys in the right-ascension interval 2h ≤ RA ≤ 6h

We search for variable objects at 3.94 GHz in the 1988–1994 surveys within the right-ascension interval 2h ≤ RA ≤ 6h. In this study we continue to develop our technique for identifying variable radio sources in the Cold surveys. We identified a total of 195 radio sources in the available sky transit scans, and only 145 objects have their flux measured in two or more surveys. To check these radio sources for variability, we estimated the indices V of long-term variability, the relative variability amplitude V χ , and the χ 2 probability p. Among the 145 objects considered, 15 have positive long-term variability indices (V >0). Of these, five sources have χ 2 probability p greater than 0.95. Three objects with p > 0.996 can be considered reliably variable sources, and two objects with probabilities 0.95 < p < 0.996 can be considered possibly variable sources. Eight objects prove to be reliably variable according to an analysis of our data combined with the flux measurements by other authors, performed within the framework of the 1980 survey. We draw the light curves for sources with positive long-term variability indices and perform optical identification of these objects.