Typical u′-band STELLA exposure of Mrk 1018 (at the centre of the image) and three reference stars. The galactic and ICRS coordinates are shown. The two stars on the left hand side are bright, and can be used to locate Mrk 1018 and the reference star on the right. The reference star on the right-hand side is used for relative photometry as it is unlikely to be saturated and has a similar u′–g′ colour to Mrk 1018.