VLBA images of 3C 138 at 23.5 GHz obtained on 2022 December 14 (a), 2024 June 18 (b), and 2025 June 21 (c). Contours are drawn at ( − 1,  1,  2,  4,  …) × 5σ, where σ is the image rms noise. The synthesized beam is shown in the lower-left corner of each panel. Yellow circles denote circular two-dimensional Gaussian model components. Their diameters represent the full widths at half maximum, and their centers mark the component positions.