Okay, so. Here's what I know: the last three days of the Greek lunar calendar's months were all considered to be the best days with working with the “lower world,” or the cthonic world, or the world of the dead. Or whatever. These were oriented around the new moon.
However: the specifics of how the Greek lunar calendar worked? No idea about those. I'm aware that our idea of what the new moon is divergent from what a fellow in ancient Greece would have meant, as well.
Nonetheless, I still find myself desiring to know when those days are, and orient the dedications I make to the dead and work of similar matters around that time-frame. As such: is anyone aware of where I might find more information on this subject? Even better, is there a website that would transpose such a calendar with our current Gregorian one?