2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/4914Observations of the red giant Arcturus (Alpha Boo) obtained with the star tracker on the Wide Field Infrared Explorer (WIRE) satellite during a baseline of 19 successive days in 2000 July-August are analysed. The power spectrum has a significant excess of power at low-frequencies. The highest peak is at about 4.1 micro-Hz, which is in agreement with the ground-based radial velocity and photometry study of Belmonte et al. (1990a; 1990b). The variability of Arcturus can be explained by sound waves, but it is not clear whether these are coherent p-mode oscillations.4 pages, 1 Latex file, 3 .eps figures, uses 2 Kluwer .sty files (klucite.sty, klups.sty). To appear in `Asteroseismology Across the HR Diagram', Kluwer (Astrophysics and Space Science Series, eds. Thompson M.J., Cunha M.S., Monteiro M.J.P.F.G., 2003Astrophysicstext