Normalize bandpass weights to support integration “in K_RJ”
Bandpasses are assumed to be in power units, i.e. Jy/sr this function takes the input weights and multiplies them by the conversion factor from RJ to Jy/sr, so that when we do the integration with foregrounds defined in RJ units using these weights, we first convert to power and do the integration in power. Then they are also all multiplied by the integrated conversion factor from Jy/sr to RJ, so that the output of the integral is transformed back to RJ.
array of frequency in GHz, without units
array of weights, without units, if None, a top-hat bandpass (in power units) will be used