Kowal also discovered or co-discovered the periodic comets 99P/Kowal, 104P/Kowal, 134P/Kowal-Vavrova, 143P/Kowal-Mrkos, and 158P/Kowal-LINEAR.
Med najbolj pomembnimi so:* atonski asteroid 2340 Hator,* apolonski asteroidi1981 Midas, 2063 Bakhus, 2102 Tantal in (5660) 1974 MA* amorska asteroida (4596) 1981 QB in (4688) 1980WF* trojanska asteroida 2241 Alkatus in 2594 Akamas.