Comet Donati–Toussaint, formally designated as C/1864 O1, is a non-periodic comet co-discovered by Italian astronomers, Giovanni Battista Donati and Carlo Toussaint in July 1864.
Discovery and observations.
On the night of 23 July 1864, astronomers Giovanni Battista Donati and Carlo Toussaint spotted a new comet within the constellation Coma Berenices. Their discovery was confirmed four days later on July 27. Although it never came close to either the Sun or the Earth to allow itself to become a bright object, astronomers were able to observe it until 25 February 1865, and thus were able to determine its orbit with higher precision.