A rapid millimetre wave outburst in the nucleus of NGC1275

A very rapid large-amplitude outburst was observed in the Seyfert-like galaxy NGC1275 at millimetre wavelengths but not at lower radio frequencies. At 89.6 GHz, the flux density rose from 42 Jy to 75 Jy between 26 October 1979 and 13 March 1980 at a rate reaching 140 Jy yr−1. The event was also evident at 1 mm wavelength, where the flux density increased from 24 Jy to 64 Jy between measurements made on 11 Jan 1979 and on 28 March 19801. Observations at 31.4 GHz limit any simultaneous outburst to 20 Jy or less. This is the first time a strong outburst has been seen at millimetre but not centimetre wavelengths in any radio source.