Four typical light curves for variable stars (black dots K, gray dots H). The dashed lines represent two nearby nonvariable stars in K. From top to bottom, the individual panels show the following cases: a) Irregular variability, typical for most variable sources in this data set. b) Irregular variability with high amplitude and outburst. c) Candidate periodic star, representative of 13% of variables. d) Slow brightness change with possible periodic behavior, which can be found in 9% of variable sources.