Four-parameter association of nonvariable stars with our identified sample of RR Lyrae variables (blue crosses) in the Orphan stellar stream. Similar to Fig. 3, the color coding denotes the membership probabilities p(A|B) in coordinate (bottom left panel), proper motion (upper panels), and systemic velocity (bottom right panel) space. The gray lines and shading represent the Gaussian process regression and confidence intervals (CIs), respectively. The three error bars at the bottom of each panel denote the 15.9, 50, and 84.1 percentiles of the uncertainties on individual parameters.