Abstract. The spectrum of the solar corona, plasma spectra, astrophysical objects and fusion devices exhibit forbidden lines in alkali-like ions. Ions belonging to the iron group are particularly important in this respect. More accurate data for term values, line strengths and transition probabilities are reported for electric quadrupole (E2) transitions in the highly stripped ion CoXVII using highly correlated relativistic wavefunctions obtained by coupled cluster theory. The present results are consistent with the findings of the earlier theoretical data. Some of the data are reported for the first time.