Integrated flux densities of nine bright sources between 44 MHz and 1.4 GHz in the field of view of the LOFAR observation of the Perseus cluster. The sources in this figure are marked with a circle in Fig. B.2. The lowest frequency point is the flux density measured in this work. The other surveys used in this figure are (in order of increasing frequency) are: VLSSr (74 MHz; Lane et al. 2014); TGSS ADR1 (150 MHz; Intema et al. 2017), WENSS (330 MHz; Rengelink et al. 1997) and, NVSS (1.4 GHz; Condon et al. 1998).