# A “strange” unit radio astronomy

I'm reading up on radio astronomy, and I came across this paper from 1964. At the bottom of page 193, the author uses a unit that I've not seen before in discussing radio power emission from stars:

Now the outbursts on the Sun give an intensity on Earth of $$10^{19}$$ to $$10^{20}$$ $$wm^{-2}(c/s)^{-1}$$

I'm guessing it's "Watts per square meter per [something] per second", but I'm not sure what the [something] is.

A similar unit appears in this paper on the first line on page 364:

The comparison band in the radiometer, being separated approximately 3.25 Mc from the signal band, never encounters the hydrogen range of frequencies.

Again, this looks to me like mega[something]. Can anyone shed some light on this?

On page 362 of the second paper, the unit appears as $$(Watts/M^2 )/(C/S)$$ as a unit of flux. There, the $$C$$ looks like coulombs, but that makes the $$3.25 Mc$$ in the second quote seem weird.

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.