Simultaneous observations of a strong auroral display by the VIKING ultraviolet imager and a meridian scanning photometer of the CANOPUS array have been obtained. These show good overall agreement between the latitude profiles inferred from the data of the two instruments and provide evidence that the images are correctly located in geographic coordinates. The relation between imager signal for vertical viewing and the 4278¿ N2+ band brightness as observed from the ground has been determined. A modelling study shows that this relation is sensitive to incident electron energy and could vary by a factor of about 5 for electron energies between 2 and 10 keV. The modelling combined with provisional absolute wavelength sensitivity curves for the imager leads to values in the same range as that from the ground comparison. ¿American Geophysical Union 1987