Was also Cinco de Mayo which received more fanfare. Books and Culture reprinted an article about it and mentions a book,Ascension and Ecclesia: On the Significance of the Doctrine of the Ascension for Ecclesiology and Christian Cosmology (T&T Clark/Eerdmans, 1999), by Doug Farrow.
Books & Culture Corner: Taken Up in Glory - Books & Culture
I too am puzzled by why this particular event is so often ignored. It may have to do with the concomitant future event for which the ascension sets the stage and which has been popularized in the Left Behind Series. And I am not talking about this!