The telescope was used primarily by Pietro Tacchini, assistant astronomer from 1863 to 1879, who employed it to launch pioneering solar physics research that would mark the birth of Astrophysics. These interests led Tacchini, together with Father Angelo Secchi, director of the Observatory of the Collegio Romano (whose plaster bust by sculptor Domenico Costantino is preserved in the Merz Room), to found the Società degli Spettroscopisti Italiani in 1871—the first professional society dedicated specifically to astrophysics.
Today, the room has been completely renovated and houses instruments for spectroscopy and geomagnetism—the former used in combination with the Merz telescope, the latter for studying solar activity and its relationship with variations in Earth's magnetic field.
