HIGH-PRECISION, LONGITUDINAL, DISC-AVERAGED MAGNETIC-FIELD MEASUREMENTS OF ALPHA-CANIS-MINORIS AND BETA-LEPORIS

High-precision longitudinal, disc-averaged magnetic field measurements have been made on two late-type stars, alpha CMi (HR 2943) and beta L ep (HR 1829). A magneto-optical filter has been used to measure the de gree of circular polarization in the wings of a line of neutral potass ium (7699 Angstrom) formed in the atmosphere of the target star. From 10 nights of data taken on alpha CMi on the 1.9-m reflector at the Sou th African Astronomical Observatory (SAAO) in 1993 January, an upper l imit to any net longitudinal field component present-assuming the fiel d to be constant over the period of observation-of -0.40 +/- 0.26 G wa s established. Similarly, upper limits for beta Lep of -4.3 +/- 6.4 G and -0.7 +/- 1.6 G were established, from 4 and 10 nights of data take n in 1992 and 1993 January respectively. No significant, periodic, day -to-day variations were seen in the three time series of data.