(C − R) colour maps of NGC 3585. The top panel shows the entire galaxy and has the same dimensions as Fig. 1 (~15′ × 15′). The colour range shown is 1.1 ≲ (C − R) ≲ 2.5, with bluer colours darker, and redder colours lighter. It is clear that no strong colour gradient is present out to large radii. The lower panel shows the inner  ~75″ × 75″ over a colour range of 1.73 ≲ (C − R) ≲ 1.85. The  ~ 45″ discy structure discussed in the text is clearly visible. The noisy rectangular region surrounding the galaxy core is the short exposure that was used to replaced the overexposed central region (see Sect. 3) and does not affect the colour profile in any way.