SIMBAD references

The spectrum of Cepheus A in the 5₁⟶6₀A⁺ transition was observed 19 times during a 750 day interval beginning in 1993 using the Penticton 25.6 m diameter antenna. Two of the five spectral components exhibit large changes in intensity. The amplitude ratio of the lines at -3.8 and -4.2 km/s changed from 1.4 to 0.8 over 2 yr. Three spectra published by other authors between 1991 and 2000 confirm that these lines are indeed variable, although the variability does not follow the quasi linear trend inferred from spectra presented here.