Janus was observed by Dan Pascu on 19 February 1980 (S/1980 S 1,) and then by John W. Fountain, Stephen M. Larson, Harold J. Reitsema and Bradford A. Smith on 23 February 1980 (S/1980 S 2.)
U vërejt edhe nga Dan Pascu me 19 shkurt 1980 (S/1980 S 1), e pastaj nga John W. Fountain, Stephen M. Larson, Harold J. Reitsema and Bradford A. Smith me 23 shkurt, (S/1980 S 2.)