telescope scheduling, though we tried to include extra nods for sources expected to have lower flux densities.

### GBT flux density determinations

The CCB has a 14GHz bandwidth, split into four frequency sub–bands centred at 27.75, 31.25, 34.75 and 38.25GHz. We can thus measure simultaneously four separate flux densities for each source, from which we can derive a 30GHz value by fitting a power law to the available data. We use a Monte–Carlo method to estimate the uncertainties on the interpolated flux densities. For poor–quality data, we were unable to derive accurate 30GHz flux densities from the GBT data alone, as discussed in Section \[sec:add\]

Determining the 30GHz flux densities {#sec:add}
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The quality of our GBT data is rather mixed due to the wide range of observing conditions experienced. As most sources were only observed once, we are also unable to constrain source variability with GBT data alone. In order to supplement our 30GHz measurements, we make use of the flux densities reported in [@Coble2007] who observed all of our clusters except Abell 2390 at 28.5GHz with the OVRO and BIMA interferometers. Such interferometric data not only measure the SZ effect but also enable identification of point sources via 