3. Lightcurves, amplitudes, mean magnitudes and colors
For each variable, the lightcurves in B and V were fitted by means of smoothing splines, shown as a solid line in the quoted figures. From these fits we finally derived for the three RR Lyrae stars the amplitudes in V and B and the mean magnitudes and colors reported in Table 5. Fig. 4 (top) compares the present lightcurve for AQ Lyr with previous measurements given by Sturch (1966), while Fig. 4 (bottom) compares the lightcurve for CN Lyr with the photometry given by Oosterhoff (1962). One finds a reasonable agreement together with evidence for the great improvement achieved by the use of CCD even in rather small telescopes as the one used in this investigation.
As a final point, one may compare present results with the rich sample of lightcurves presented by Lub (1977) for field stars. For each of our 3 variables one finds in Lub's sample stars with similar periods and with quite similar lightcurves, supporting the reality of the various features and showing that in all cases we are dealing with "typical" field RR Lyrae pulsators.
© European Southern Observatory (ESO) 1998
Online publication: April 28, 1998