SeeingEyeD0g wrote:

Frequency: 1.8kHz to about 1.9kHz
That is just above the MW (AM) broadcast band! So expect propagation
characteristics to be best during night time hours with possible interesting
propagation occurring within the half hours before and after your local
sunset and sunrise times.

Also known as "gray line propagation", when the terminator passes over
your location. And yes, it really does work. I qso'ed Hawaii from
Michigan on 160 a few times via gray line...

After the sun comes up, the D-layer absorption goes waaay up and 160
(and the BC band) is basically good for ground wave only.