Left: NOT images (in Hα and [O iii] 5007 Å light) of the planetary nebula we discovered around the symbiotic star DT Ser. North is up, east to the left, and the overall diameter of the nebula is 11.4 arcsec. Stars A and B (5 arcsec away) that are mentioned in the text are identified. The 225° and 135° slit positions, centered on star A, are also identified. Positions S-E and N-W are referred to in Fig. 4 and the text (Sect. 5). Center: portion of the original 2D Echelle spectra for the 225° slit position centered on Hα and [O iii] 5007 Å. Right: the same for the 135° slit position.