Original: Themisto was first discovered by Charles T. Kowal and Elizabeth Roemer on September 30, 1975, reported on October 3, 1975, IAUC 2845: Probable New Satellite of Jupiter 1975 October 3 (discovery) and designated.
Simplified: Themisto was first found by Charles T. Kowal and Elizabeth Roemer on September 30, 1975, reported on October 3, 1975IAUC 1975 October 3 (discovery) and designated.