Many thanks to Chris Smolinski, from the HF Underground, who has crunched some numbers from North American pirate radio loggings on Halloween. The number of pirates (and his charts with times and frequencies) are most impressive and informative.
Chris posted the following on the HF Underground and has kindly allowed me to share them here as well. Chris notes:
Here are two charts showing who-was-on-when-and-where this Halloween.
The first one is for Friday night:
And the second is Halloween (Saturday) night: