A 43 GHz VLBA image of BL Lac on 2015 May 11. Contours start from −1, 1, 2 (and so on) times 1.7 mJy beam⁻¹ and increase by factors of (negative contours are coloured in red). The beam size is shown at the bottom-right corner of the plot and is 0.325 mas by 0.208 mas at PA 20.6°. The peak flux density of the map is 1.88 Jy beam⁻¹. The image also superposes a set of best-fitted circular Gaussian components – A0(=core), A1, A2, J1 and J2. A0, A1 and A2 are well-known stationary features located at the core, ∼0.14 mas and ∼0.3 mas away, respectively (see e.g. Wehrle et al. 2016).