PULSATIONAL BEHAVIORS OF THE DELTA-SCUTI STARS HD-18878 AND HD-19279

A set of 2915 V measurements covering 146 hours of the delta Sct star HD 18878 was obtained at Merate Observatory on 25 nights from November, 1990 to January, 199 1. The light curve is dominated by the first term (f1 = 6.86 c/d) which displays an amplitude of 23.4 mmag, but the frequency analysis unambiguously revealed three components with amplitudes between 4.6 and 8.4 mmag (f2 = 11.22 c/d, f3 = 11.18 c/d, f4 = 10.01 c/d) and, with a lower reliability, three components with amplitudes between 2.7 and 4.6 mmag (f5 = 12.29 c/d, f6 = 13.20 c/d, f7 = 10.78 c/d). Other undetected terms with amplitudes lesser than 1.6 mmag are probably present. The most probable identification for the f1 term is the fundamental radial mode and also the f6 and f7 terms can be radial modes (the third and second overtones, respectively); the other are surely nonradial modes. During the first nights of observations, HD 19279 was used as a comparison star and it was found to be variable. Further intensive observations showed that this star is a very small amplitude (2.1 mmag), monoperiodic (f1 = 14.45 c/d) delta Sct variable.