1           1981-11-16.92  Zappala et al. (1983) 
2           1981-11-17.94  Zappala et al. (1983) 
3           1981-11-18.93  Zappala et al. (1983) 
4           1981-12-02.25  Harris et al. (1992) 
5           1981-12-03.26  Harris et al. (1992) 
6  1996-12-30--2012-02-26  Lowell