Ground-based auroral observations with a meridian-scanning photometer and all-sky camera were made at Rabbit Lake, Saskatchewan, canada, simultaneously with nearby HILAT satellite passes during six winter periods near new moon 1984 to 1986. Eight passes were selected in which HILAT overflew auroras visible from Rabbit Lake. Auroral intensity measurements made at Rabbit Lake were corrected for proton aurora and nightglow and compared with HILAT electron flux measurements at 800 km. The excitation efficiency for the 4278-¿ auroral emission by electron precipitation was found to be (0.29¿0.08) kR/(erg/cm2 s). Excitation efficiencies for 5577-¿ emission of (1.73¿0.51) kR/(erg/cm2 s) and (1.23¿0.44) kR/(erg/cm2 s) were measured on different ⋅ days in auroras excited by 1.8-keV and 3.1-keV Maxwellian precipitation during moderate geomagnetic disturbance. After small night-to-night variations in atmospheric composition indicated by the MSIS-86 model atmosphere were accounted for, the magnetic zenith column intensity ratio 6300/4278 was found to depend on the electron characteristic energy E0 approximately as 6300/4278-3.3 E0-2.1 for characteristic energies of a few keV. The 5577/4278 ratio was found to decrease by about 40% from 1 to 4 keV characteristic energy. These results pertain mostly to weak auroras (I(5577 ¿)=2--6 kR). Most of these new measurements agree fairly well with previous results of other workers, but the two 5577-¿ excitation efficiencies and the decreasing 5577/4278 intensity ratio show that the green line excitation efficiency varies appreciably even for small changes in the precipitating electron spectrum and atmospheric composition. Published calculations of the auroral 6300/4278 and 5577/4278 ratios versus characteristic energy are compared with our measurements. The magnitude and variation of the 5577/4278 ratios are consistent with roughly 60% of green line emission resulting from O(1S) excitation by N2(A) energy transfer. ¿ American Geophysical Union 1990