lower frequency measurement, and proceed as for source 1. For source 2 in A2219, we again fit a power law to the OVRO/BIMA and NVSS datapoints. Source 6 in A68 does not appear in any of the lower frequency catalogues but is well measured by OVRO/BIMA. It is outside the OCRA beams so its flux density has only a small effect on the SZ measurement. Both sources in A773 are faint in NVSS and are not detected by OVRO/BIMA. The noise on the OVRO map is $0.078$mJy, giving a $5 \sigma$ upper limit of $0.39$mJy. As the sources in A773 lie well away from the OCRA beams, we are confident that their effects on our data are negligible.

Source corrections {#sec:corr}
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Due to OCRA-p’s position switching strategy, contaminant radio sources can affect the data by producing a *positive* signal when they lie close to the cluster centre, or a rogue *negative* signal when they lie in the reference beam of the telescope. We simulate the effects of the sources based on their measured positions and flux densities, and the OCRA beam response. We then use the resulting effective flux density to correct the SZ data. Contamination through sources at 