The calculated distance (air line) between Doğubayazıt and Vagharshapat is approximately 44 miles respectively 71 kilometers.
By car or train, the actual journey to Vagharshapat is certainly longer, as only the direct route (as the crow flies) between Doğubayazıt and Vagharshapat has been calculated here.
Air line (approximately)
71 kilometers
38 nautical miles