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1.
A person who gazes at the female ass and who observes with detail how the ass moves when walking. An asstronomer also tracks the tail as it passes by.
Matty had to study Uranus before he was considered to be an asstronomer.
by bentwood021 March 30, 2010
 
2.
A proctologist who is so very into his profession, quite likely because of himself being gay.
God I went to the proctologist today and man, he wouldn't finish checking my ass for 6 hours already! What an asstronomer! Next time I go see a proctologist, I should ask him if he's gay or else if he is I won't let him examine my ass.
by Mark H June 11, 2004
 
3.
(n.) a person, usually a man, who is interested in the field of ass (usually female).
herbert was an avid asstronomer; he could determine the exact gravitational pull of an ass just by looking at it.
by carlos c March 03, 2008