1994A&A...289..162B

Multisite photoelectric B and V photometry of the δ Scuti star 63 Her was obtained on three continents. Three frequencies of pulsation (f₁=11.32, f₂=20.07 and f₃=7.72 c/d) were detected with a signal/noise amplitude ratio ≥4.0. The three frequencies fit all the available data ranging back to 1968. Reports in the literature of discrepant behavior of the 1968 measurements were probably caused by overinterpretation. The new frequency values are in excellent agreement with the results found by Reed & Welch from their 1983 data, except for a 1 c/d alias in their value for f₂. Two additional pulsation frequencies in the low-frequency g-mode domain with amplitudes near two millimag reported by the STEPHI group are not seen in the new campaign data. The new data show average noise levels just below one millimag in this frequency domain, so that the existence of these two frequencies cannot be disproved from the new data alone. However, a reanalysis of the STEPHI data also suggests that these frequencies might not be real. The results from the two multisite campaigns should be free of 1 c/d aliasing, so that a resonance hypothesis involving f₂=f₁+f₃ can be rejected. The value of the pulsation constant associated with f₃, Q=0.046±0.008d, is too high by 2 standard deviations to be explained by radial pulsation. The Q value is incompatible with those of nonradial p₁ to p₄ modes commonly found in δ Scuti stars.