COMMISSION 27 OF THE I.A.U. INFORMATION BULLETIN ON VARIABLE STARS Number 3211 Konkoly Observatory Budapest 4 July 1988 HU ISSN 0374 - 0676 VBI LIGHT CURVES OF CC And *1 The delta Scuti type pulsating variable CC And was found by Eggen and Lindblad (1953) to have a period of 0.1249 days and a light amplitude V varying between 0.11 and 0.32 magnitudes. Fitch (1960) found a maximum yellow light curve amplitude of 0.25 magnitudes in the fundamental mode. Three other periods due to resonance-excited modes were also detected. Fitch also found a beat period of 5.233 days, based on observations over twenty seven nights. As part of an ongoing study of large-amplitude delta Scuti stars at the University of Calgary, and in fulfillment of their observing requirements in a senior undergraduate astrophysics laboratory course, C.R. and J.I.B. observed CC And on two nights: 1987 September 28 (85 observations) and October 4 (59 observations) U.T.. The observations were obtained with the 41 cm Cassegrain telescope of the Rothney Astrophysical Observatory near Calgary, Alberta, Canada, using a cooled RCA 31034 gallium-arsenide photomultiplier tube and V, B, I filters closely matching the standard Johnson system. The RADS differential photometry system (Milone et al., 1982) was operated in the 4-channel mode. The comparison star was BD +41d123 (SAO 036623) which has spectral type G5. The differential airmass was less than 0.002 throughout so that the differential extinction was negligible. The integration time was varied between 7 and 10 seconds depending on sky conditions (principally transparency) which were more photometric on September 28 and less so on October 4. The observations covered 2.4 cycles and 1.1 cycles on the first and second night respectively. The light curve amplitudes for the different filter bands for each night are shown in Table I. The overlap of consecutive cycles increases the scatter of the data. Minimum light occurs Phi approx. 0.55 and maxima occurs at Phi approx. 0.00 for all curves, with the ephemeris given by Wilson and Walker (1956). [FIGURE 1] Figure 1 Fourier Fits Plotted on V, B and I Luminosity Curves for CC And on 1987 September 28 and October 4 U.T.. A five-term truncated Fourier series of the form: L=A_0+A_1 cos Theta+A_2 cos 2Theta+B_1 sin Theta+B_2 sin 2Theta was fit to the luminosity data using the relation: L=L_0*10^(-0.4(m-m_0)) where m_0 is the mean magnitude at maximum brightness and L_0 is normalized to unity. See Table II for Fourier constants, coefficients and error in the fit. Figure 1 shows the Fourier fits plotted on the luminosity data. Table I Photometric results for CC And on 1987 September 28 and October 4 U.T. Julian Date Filter Amplitude sigma 2447066.844 V 0.175 0.015 2447066.844 B 0.230 0.018 2447066.844 I 0.109 0.014 2447072.820 V 0.180 0.022 2447072.820 B 0.299 0.039 2447072.820 I 0.111 0.022 Table II Fourier constants, coefficients and fit error for all light curves JD Filter A_0 A_1 A_2 B_1 B_2 Chi^2(mags) 2447066 V 0.91210 0.07702 0.00429 -0.00467 -0.00594 0.0125 2447066 B 0.89495 0.09741 0.00288 -0.00805 -0.01391 0.0179 2447066 I 0.94576 0.05220 0.00069 -0.00154 -0.00819 0.0130 2447072 V 0.90942 0.07631 0.00886 0.00332 -0.00443 0.0200 2447072 B 0.86795 0.11079 0.01442 0.00395 -0.00877 0.0295 2447072 I 0.94052 0.04415 0.01270 0.00379 -0.00788 0.0186 The present data were calculated to be at 0.15 and 0.29 phase respectively in the beat period of Fitch (1960). The corresponding predicted visual amplitudes are 0.19+/-0.02 and 0.22+/-0.02 magnitude. Our observed V and I light curves show a trend towards larger amplitude at 0.29 of the beat period although the increase is not as significant as the expected long period amplitude. The B filter band however, does show a clear variation in amplitude. *1 Publication of the Rothney Astrophysical Observatory, Series B, No. 13. C. ROUSSEAU, J.I. BOURASSA and E.F. MILONE Rothney Astrophysical Observatory Physics Department University of Calgary Calgary, Alberta Canada T2N-1N4 References: Eggen, O.J.E., Lindblad, P.O., 1953, Publ, Astr. Soc. Pacif., 65, 291. [BIBCODE 1953PASP...65..291L ] Fitch, W.S., 1960, Astrophysical Journal, 132, 701, [BIBCODE 1960ApJ...132..701F ] Milone, E.F., Robb, R.M., Babbott, F.M., Hansen, C.H., 1982, Applied Optics, 21, 2992. [BIBCODE 1982ApOpt..21.2992M ] Wilson, O.C., Walker, M.F., 1956, Astrophysical Journal, 124, 325. [BIBCODE 1956ApJ...124..325W ]