Please note that the content of this book primarily consists of articles available from Wikipedia or other free sources online. 35P/Herschel Rigollet is a periodic comet discovered by Caroline Herschel on 1788-12-21. aroline Herschel first observed the comet on 21 December 1788 and it was observed later that night by her brother William Herschel who described it as looking like a bright nebula and about 5-6 minutes in diameter, and much larger than the planetary nebula M57. Through December and January the comet was observed by Nevil Maskelyne at the Greenwich Observatory and by Charles Messier at the Paris Observatory. Maskelyne was the last observer of the comet, his final observation taking place on 1789-02-05.