Cyanoacetylene (HC3N) was detected in
1971 in Sgr B2 by
Barry Turner. Confirming observations include the detection of a
second rotational line by Dickinson in 1972,
a third line by McGee et al. in 1977, and
detections of two of the 13C isotopomers by
Gardner & Winnewisser in 1975.
The first extragalatic detection was reported in 1990 by
Mauersberger et al.
toward the Silver Dollar galaxy. In was also observed in comet
Bockelée-Movan et al. and also in Titan's
Kunde et al., making it one of the most diversely
observed astromolecules to date.
UPDATE (July 2018): Cyanoacetylene was detected in the protoplanetary disk
MWC 480 by
Chapillion et al. in 2012.
Cyanoacetylene is the prototype of one
of the most extensive family of known interstellar species, the
cyanopolyynes, which consist of
H-(CC)n-CN for n greater than 1.