Photometric measurements of H-beta in the aurora

Measurements of auroral H-beta at high temporal and spatial resolution obtained by means of an interference filter scanning photometer have been subjected to a detailed analysis regarding possible sources of signal contamination. Two general categories of potential contamination were investigated: (1) strong spectral emmisions within the 'wings' of the filter passband and (2) weak molecular bands, atomic lines continuumunderlying the H-beta line and therefore contributing to the light passed by the filter. Calculation of the apparent intensity resulting from contamination in the first category yielded an upper limit of 10 R false H-beta signal for the brightest auroral conditions when H-beta intensities are on the order of 1 kR. Estimates of intensities resulting from contamination of the second category were calculated from two points of view: (a) examination of spectral morphology, with a result that 60–70 per cent of the signal recorded is true H-beta and (b) estimation of individual contaminating emssions with a result that at least 65 per cent of the recorded signal is auroral H-beta.