COMMISSION 27 OF THE I. A. U. INFORMATION BULLETIN ON VARIABLE STARS Number 2011 Konkoly Observatory Budapest 1981 August 28 HU ISSN 0374-0676 PHOTOELECTRIC OBSERVATION OF delta CAPRICORNI Delta Cap has been known as a single-lined spectroscopic binary of metallic-line features. The eclipsing nature of this system was first announced by Eggen (1956) from his V_E observation, which indicated a depth of 0.16m in visual region for the primary minimum. Wood and Lampert (1963) also observed the primary eclipse photoelectrically. However, the secondary minimum has never been published so far. BV observations were made on thirteen nights in 1977-80 with the 8-inch refractor at the Education Centre of Kanagawa Prefecture, Japan. The photoelectric photometer was furnished with a 1P21 photomultiplier tube and two colour filters, Schott BG12+GG13 for B and Schott GG41 for V. gamma Cap was used as the comparison star throughout the course of the observations. This comparison star is the same as previously used by Eggen and Wood and Lampert. The present observations cover the primary minimum and touch the mid-secondary minimum. All the results of observations expressed in m_v - m_c are given in Table I, where the phases are calculated with Prim. Min. - JD 2435656.911 + 1.022768 E Which has been taken from the General Catalogue of Variable Stars (1969). The observations are also plotted in Figure 1. The depths of both minima are deduced as shown in Table II. The observed epoch of the mid-eclipse is JD(Hel) 2443832.924, which gives + 0.006d ( E=7994) for O-C residual from the above ephemeris. The light variation in B outside eclipses can be expressed by l = 0.9811 - 0.0190 cos 2 Theta. From the coefficient 0.0190 for the cos 2 Theta term, the ellipticity of the components can be deduced to be Z = 0.037 according to the procedure of Russell and Merrill (1952). [FIGURE 1] Table I BV Photoelectric Observations of delta Capricorni ------------------------------------------------- Date Hel. JD DeltaV DeltaB Phase 2440000+ 1977 ------------------------------------------------- Sep.20 3407.0590 -0.853 -0.865 0.6207 .0636 -0.843 -0.860 0.6252 .0684 -0.838 -0.855 0.6299 .0725 -0.856 -0.867 0.6339 .0769 -0.854 -0.865 0.6382 .0814 -0.855 -0.866 0.6426 .0861 -0.854 -0.867 0.6472 Nov.27 3474.9494 -0.785 -0.815 0.9494 .9012 -0.783 -0.815 0.9527 .9082 -0.790 -0.797 0.9595 .9116 -0.780 -0.795 0.9629 .9155 -0.756 -0.770 0.9667 .9196 -0.736 -0.748 0.9707 Dec.01 3478.8796 -0.854 -0.876 0.8425 .8827 -0.854 -0.879 0.8456 .8857 -0.859 -0.860 0.8485 .8883 -0.850 -0.860 0.8510 .8910 -0.848 -0.868 0.8537 .9001 -0.847 -0.854 0.8626 .9033 -0.842 -0.860 0.8657 .9192 -0.847 -0.850 0.8724 02 3479.8848 -0.854 -0.877 0.8253 .8886 -0.854 -0.880 0.8291 .8918 -0.852 -0.875 0.8322 .8993 -0.851 -0.873 0.8395 .9026 -0.854 -0.862 0.8427 03 3480.8938 -0.855 -0.876 0.8119 .8979 -0.856 -0.867 0.8159 .9058 -0.857 -0.872 0.8236 1978 Oct.23 3804.9484 -0.852 -0.855 0.6527 .9522 -0.850 -0.863 0.6564 .9562 -0.851 -0.871 0.6603 .9617 -0.843 -0.876 0.6657 .9670 -0.845 -0.875 0.6708 .9722 -0.856 -0.871 0.6759 .9778 -0.856 -0.872 0.6814 .9872 -0.857 -0.874 0.6856 .9868 -0.859 -0.885 0.6902 .9917 -0.850 -0.866 0.6950 Nov.20 3832.8859 -0.736 -0.775 0.9682 .8911 -0.721 -0.757 0.9733 .8971 -0.681 -0.729 0.9792 .9057 -0.660 -0.687 0.9876 .9102 -0.657 -0.665 0.9920 .9166 -0.632 -0.664 0.9982 .9236 -0.630 -0.674 0.0052 Dec.01 3843.8678 -0.862 -0.876 0.7057 .8719 -0.851 -0.877 0.7097 .8793 -0.861 -0.874 0.7169 .8828 -0.860 -0.873 0.7203 .8891 -0.853 -0.882 0.7265 1979 Oct.14 4160.9633 -0.862 -0.892 0.7423 .9665 -0.861 -0.895 0.7454 .9727 -0.863 -0.876 0.7514 .9771 -0.876 -0.882 0.7557 .9807 -0.862 -0.885 0.7593 .9850 -0.861 -0.881 0.7635 .9891 -0.864 -0.876 0.7682 .9929 -0.876 -0.874 0.7712 4161.0005 -0.857 -0.870 0.7786 .0046 -0.869 -0.886 0.7826 .0085 -0.878 -0.880 0.7864 .0125 -0.858 -0.868 0.7904 .0170 -0.853 -0.874 0.7949 .0248 -0.856 -0.872 0.8024 .0289 -0.862 -0.878 0.8063 .0325 -0.862 -0.862 0.8099 .0362 -0.861 -0.878 0.8135 21 4167.8871 -0.776 -0.768 0.5119 .8951 -0.784 -0.786 0.5197 .8993 -0.787 -0.779 0.5239 .9035 -0.800 -0.794 0.5280 .9076 -0.796 -0.792 0.5320 .9166 -0.799 -0.798 0.5408 .9209 -0.800 -0.802 0.5450 .9248 -0.806 -0.817 0.5488 .9307 -0.809 -0.812 0.5546 ,9340 -0.810 -0.828 0.5578 .9434 -0.811 -0.815 0.5670 .9477 -0.815 -0.825 0.5711 .9552 -0.821 -0.842 0.5785 .9716 -0.833 -0.853 0.5945 .9799 -0.847 -0.864 0.6027 .9831 -0.846 -0.859 0.6058 Nov.13 4190.8888 -0.610 -0.662 0.0016 .8929 -0.617 -0.678 0.0056 .8968 -0.632 -0.673 0.0094 .9017 -0.674 -0.679 0.0142 .9057 -0.701 -0.692 0.0181 .9103 -0.696 -0.724 0.0252 1980 Sep.29 4512.0103 -0.684 -0.728 0.9746 .0298 -0.638 -0.663 0.9937 .0578 -0.665 -0.689 0.0209 .0633 -0.699 -0.711 0.0264 Oct.04 4517.0235 -0.840 -0.854 0.8761 .0343 -0.830 -0.858 0.8867 .0433 -0.833 -0.848 0.8955 .0477 -0.833 -0.844 0.8998 -------------------------------------------------- Table II ---------------------------------- Depths of the Minima in BV DeltaB DeltaV ---------------------------------- Primary minimum 0.217 0.147 Secondary minimum 0.114 0.090 ---------------------------------- I would like to express my hearty thanks to Prof. M. Kitamura of Tokyo Astronomical Observatory for his suggestion of this programme and kind guidance. Thanks are also due to Mr. H. Ogata at Fujisawa Education Office for his encouragement. SHIGEO OHMORI Education Centre of Kanagawa Prefecture, Fujisawa-City, Fujisawa 4210 Kanagawa, 251 Japan References: Eggen, O.J. 1956, Publ. A.S. Pacific, 68, 542. [BIBCODE 1956PASP...68..541E ] Kukarkin, B.V., Kholopov, P.N., Efremov, Yu. N., Kukarkina, N.E. Medvedeva, G.I., Perove, N.B., Fedorovich. V.P., and Frolov, M.S. 1969, General Catalogue of Variable Stars (Astrn.Council Acad. Sci. USSR, Moscow). Russell, H.N. and Merrill, J., 1952, Contr. Princeton Univ. Obs. No. 26. [BIBCODE 1952deeb.book.....R ] Wood, F.B. and Lampert, G. 1963, Publ. A.S. Pacific, 75, 281. [BIBCODE 1963PASP...75..281W ]