Constraining the period of the ringed secondary companion to the young star J1407 with photographic plates 由 Mentel, RT, Kenworthy, MA, Cameron, DA, Scott, EL, Mellon, SN, Hudec, R, Birkby, JL, Mamajek, EE, Schrimpf, A, Reichart, DE, Haislip, JB, Kouprianov, VV, Hambsch, F-J, Tan, T-G, Hills, K, Grindlay, JE, Rodriguez, JE, Lund, MB, Kuhn, RB