A "strange" unit radio astronomy
I would expect the authors to be talking about the signal in terms of janskys, the now-commonly-used units of flux density. The typical definition is
$$1\text{ Jansky}=10^{-26}\text{ Watts meters}^{-2}\text{ Hertz}^{-1}$$
One hertz is one cycle per second, which makes me suspect that the "c" stands for cycle. It might seem curious that the authors choose to use cycles/second instead of hertz, but as the papers were published in 1964 and 1955, and the hertz was only adopted on a large scale in 1964, the older term "cycles per second" is more fitting, given the time period.