Named for John (Jack) Locke Estens (1919– ), Australian astronomy educator. Following a life of farming, he devoted his retirement to bring astronomy to the public with his handsomely constructed observatory and lecture room in Gilgandra, N.S.W. Opened in 1975, the observatory saw a steady stream of visitors until his second retirement in 1996. Always friendly and enthusiastic, he provided a service missing at the professional observatories, with his personal tours of the night sky. (M 29143) _ _.