[“Comet Coggia 1874 observed at the Roman College”]

"Cometa Coggia 1874 osservata al Collegio Romano"
Angelo Secchi
Memorie della Società degli Spettroscopisti Italiani, volume III , 1874
Tav. LV
320 x 210 mm
Library of INAF-Palermo Astronomical Observatory

As a curious observer of all natural phenomena, Secchi could not neglect the study of mysterious objects like comets, discovering even one in 1853 (the 1853-I come) which there fore bears his name. Among the main contributions given by Secchi in this field there is the study of the Comet of Biela (1826-I): in 1852 Secchi identified the two fragments into which it splitted. In particular, Secchi was among the first astronomers who studied cometary spectra, together with Giovan Battista Donati and William Huggins: the first of cometary spectrum he studied was that of the comet Tempel-Tuttle (1866-i), which he observed in 1866, confirming the observations made by Donati who, two years earlier, had found a three-band spectrum in the Comet Tempel (1864-I), then identified as carbon compounds lines. The table shown here illustrated the observations of the Comet Coggia (1874-III), including its spectrum (bottom right), of which Secchi  studied the variations as it approached the perihelion in 1874.

Ileana Chinnici, INAF-Osservatorio Astronomico di Palermo