Chacornac discovered NGC 1988 in Taurus at Paris Observatory with a 10" refractor. He described the object as a 11 mag star with nebulosity (seen again on January 27, 1856). On November 20, 1862 the nebula had disappeared. Jean Elias Benjamin Valz (1787-1867), the director of Marseille Observatory could not find the object in 1861, noting a false image of a star. Chacornac is kown for his Ecliptical Charts.
|1||N||1988||1855||10||19||10,0||Rr||v||TAU||*||9||Chacornac||Nebuleuse variable de zeta Taureau||Comp. Rend. 56, 637 (1863)|
Chacornac's sketch of M 51, made 1862 at the 80 cm Foucault reflector of Paris Observatory