Low-degree, l=4 modes in full-disc BiSON helioseismological data

We demonstrate that some l=4 acoustic eigenmodes of the Sun are clearly distinguishable in long power spectra generated from Doppler velocity residuals collected in unimaged sunlight by the six-station Birmingham Solar Oscillations Network (BiSON). Modes covering the range n=17 to 21 have been measured in 16-month-long power spectra. They have typical amplitudes - when measured in full-disc Doppler velocity data - of less than similar to 1 cm s(-1) per root bin, and their frequencies have been determined to fractional accuracies of the order of 3 parts in 10(5). The sensitivity of the whole-disc observations to these modes - as implied by the data - appears to be approximately a factor of 2 greater than the theoretical predictions of Christensen-Dalsgaard.