COMMISSION 27 OF THE I. A. U.
       INFORMATION BULLETIN ON VARIABLE STARS
                    NUMBER 143



                                        Konkoly Observatory
                                        Budapest
                                        7 July 1966



                    LIGHT VARIABILITY
                 OF 20 CANUM VENATICORUM

        At the AAS-NASA Symposium on the Magnetic and Other 
Peculiar and Metallic-Line A Stars Robert C. Cameron suggested that
20 CVn (HD 115604 [F0] : alpha = 13h 13.1m, delta= +41deg 6' [1900]) might
be a Delta Scuti type star because it showed high metal indices. To
investigate this suggestion we have observed it photoelectrically with
a twelve inch reflector on three nights. The photometer used an EMI
6094 with Schott GG13 plus Corning 5030 filters.
        Two comparison stars were used, HD 116127 and HD 114905.
There was no evidence of variation of the comparison stars during the
course of any night, although the third night was rather poor and
showed appreciable scatter. The magnitudes for HD 114905 were 
converted to values equivalent to the magnitudes of HD 116127 by 
subtracting the mean difference between the comparison stars for each
night. The mean differences for the three nights were 0.355, 0.362
and 0.347mag. The differences between the comparison stars observations
yielded a mean probable error for a single difference of 0.008m.

                          [FIGURE 1]

        The accompanying figure shows the light curves obtained for
three nights. It appears that 20 CVn is variable with an amplitude of
about 0.03 magnitude. The observations are too limited to derive an
accurate period or even to establish that the variation is periodic.
However, from the individual curves a period of about 0.13 day may
be inferred. The light variation and spectral type indicate that 20 CVn
is a Delta Scuti variable.

             June 30, 1966
                                         W. H. WEHLAU
                                S. C. N. CHEN     G. SYMONDS
                               University of Western Ontario
                                 London, Ontario, Canada