So I wonder if it actually does have to peak in the wee hours of the morning. Could it be that as the earth moves around the sun and passes through the field it is presented on the side moving toward sun up? We know that looking down from the north pole the earth rotates counter clock wise. I believe it also rotate around the sun counter clock wise from the north perspective. Therefor if it is passing through a relatively static dust field you would only see them after midnight and would peak just before sunup. Just a guess on my part.
Have some Scotch. My grandkids think it's medicine. That's what I tell them, anyway.