周期彗星64P＜スイフト・ゲーレルズ彗星＞

L. Swift (Warner Observatory, Rochester, New York, USA) was engaged in the search for nebulae when he found an object of cometary appearance on 1889 November 17.13. It was located very close to Xi Pegasi and was described as "Pretty faint, large, little elongated." Swift said no motion was detected during the next 30 minutes and he suspected it was one of two nebulae that W. Herschel discovered near this star late in the 18th century, although Swift's position did not agree. He reobserved the object on November 17.99 and noticed it had moved, whereupon he sent a discovery announcement.

Tom Gehrels (Palomar Mountain Observatory, California, USA) discovered this comet on a plate exposed with the 122-cm Schmidt telescope on 1973 February 8.29. He estimated the magnitude as 19, and described the comet as diffuse and 30 arc seconds across, with a sharp condensation, but no tail. Gehrels confirmed the discovery on February 9.30.