β Cas: Simultaneous Stromgren Photometry
International Astronomical Union Colloquium
The observations were carried out in August, 1983 using the 75 cm telescope at Sierra Nevada Observatory in Spain. This telescope is equipped with a six-channeluvbyβphotometer for simultaneous measurements inuvbyand the narrow and wide Hβchannels, respectively. The observations were collected during four nights in the fouruvbyfilters and one more night was devoted to measuringβCas in thenandwbands of the HβCrawford system. In all cases, a calibrated neutral filter was used forβCas. The
... rβCas. The comparison star was Cl=HR 9085 (V=5.m55, F0III).The analysis of frequencies was carried out using the Discrete Fourier Transform method, as described in López de Coca et al. (1984), to the observationaluvbypoints collected. The periodograms showed a principal peak atv=9.91cd−l. After prewhitening for this frequency, the resulting periodograms did not show any trace of another peak, suggesting the monoperiodic nature of this star, in agreement with Antonello et al. (1986). Under the assumption of monoperiodicity ofβCas, the classical O-C method can easily be applied. Nine times of maxima were obtained for the four nights by using the method described in Rodriguez et al. (1990), where each light maximum has been derived as an average over the fouruvbybands. When the O-C method was applied, the least squares fit converged to a linear ephemeris with the following elements: To=2445568.d5097 (±0.d0007) and Po=0.d10091 (±0.d00002). This linear ephemeris satisfactorily reproduces our data ofβCas.