The initial detection of thioformaldehyde (H2CS) was reported in 1973 by
Sinclair et al.
The 2(11)-2(12) microwave transition at 3139.38 MHz was observed in Sgr B2 with the
Parkes Observatory 64 meter telescope in
New South Wales, Australia. This was the
first interstellar species
detected "by a group outside the USA." The
Parkes facility may be the only radio telescope in the
world to be the subject of a major motion picture
(The Dish) due to its role in
bringing images from the historic
moonwalk to the world.
One of the co-discoverers of thioformaldehyde,
Nicholas Fourikis, recalls a technical
problem that nearly curtailed their observations: "The phase-lock subsystem of the 9cm receiver we used
was inoperative. Without phase-locking of the receiver local oscillator it was impossible to attain
long integration times toward sources of interest. ... I stepped in to investigate the problem. Tests
I performed indicated that the fault was with the circuitry situated at the prime focus cabin of
the 64m Parkes Radiotelescope. With the aid of a multimeter and portable cathode ray oscilloscope I
proceeded exploring the circuitry associated with the subsystem. Without any familiarity of the
subsystem, it took me some time to locate the fault, a shorted resistor. After I replaced it,
the subsystem worked and we were able to detect the 2-2 transition of thioformaldehyde during the
remaining one and a half days."
A partial, tentative identification of thioformaldehyde was also reported in comet
Woodney et al.