This was part of the first night of Amanda Dawn Christie's "audio art" titled "Ghosts in the Air Glow" via the HAARP transmitter up in Alaska. It bounced around on several frequencies during the half-hour, including 4850 and 4800 kHz.
The schedule for the rest can be found here: ghostsintheairglow.space.
I was listening in with poor to fair reception here in Lake Stevens, Washington.