Radial variation of the metallicity of Malin 1. Left: metallicity using the N2 calibrator of Marino et al. (2013). Right: metallicity using the O3N2 calibrator of Marino et al. (2013). The blue circles and brown hexagons show the central regions and extended disk regions, respectively, as discussed in Sect. 2.2. The horizontal dotted green line marks the solar metallicity. The uncertainty of the N2 and O3N2 calibrations from Marino et al. (2013) is 0.16 dex and 0.18 dex, respectively.