He discovered a number of comets, including 21P/Giacobini-Zinner (parent body of the Giacobinids meteor shower), 41P/Tuttle-Giacobini-Kresak, and 205P/Giacobini.
The latter he had discovered at Nice on 4 September 1896, but it was not seen on its return, a little less than 7 years later, and was considered a lost comet and consequently designated D/1896 R2.
On 10 September 2008, amateur supernova hunters Koichi Itagaki and Hiroshi Kaneda rediscovered it, on its seventeenth return.
[1][2] In 1903, Giacobinin received the Prix Jules Janssen, the highest award of the Société astronomique de France, the French astronomical society.
He volunteered for military service in World War I and suffered the effects of poison gas.