VLT/FORS2 observations of PSR  J1357−6429 (left) and PSR  J1048−5832 (right) taken in the v_HIGH filter, with integration times of 14 700 and 24 000 s, respectively. North is at the top, east to the left. Image cutouts are 30″ × 30″ in size. The circles marks the pulsar radio (T = timing; I = interferometric) and Chandra positions derived according to our astrometry re-calibration (Sect. 2.2). Their radius account for the absolute error on the reference X-ray/radio coordinates (Table 2) and the accuracy of our optical astrometry (02). The radii of the error circles are  ~043 and  ~025 for the Chandra and radio-interferometry coordinates of PSR  J1357−6429, respectively, and  ~058,  ~022, and  ~122, for the Chandra, radio-interferometry, and radio-timing coordinates of PSR  J1048−5832, respectively. The white areas in the left panel correspond to the edges of the occulting bars used in the FORS2 frame to mask bright stars close to the pulsar position. The clumpy white structure in the right panel is part of an extended nebulosity detected in the PSR  J1048−5832 field (see Sect. 3.2). In both panels, the square (10″ × 10″) corresponds to the area shown in Fig. 3.