COMMISSION 27 OF THE I. A. U.
         INFORMATION BULLETIN ON VARIABLE STARS
                     Number 1695

                                    Konkoly Observatory
                                    Budapest
                                    1979 October 23



        LIGHT VARIATIONS OF THE Ap STAR HD 164429



     The light variability of the B9p-SiSr star HD 164429 =
BS 6718 has been ascertained by Winzer (1974) who found a period
of 0.51747d, one of the shortest known for the Ap stars. The 
magnitude and colours of HD 164429 in the UBV system, as given by
Cowley et al. (1969), are V = 6.44, B-V = -0.06 and U-B = -0.17.
     Photoelectric observations of HD 164429 have been carried
out at the Catania Astrophysical Observatory in 1978 and 1979
with the 91 cm Cassegrain telescope equipped with an unrefrigerated 
EMI6256 S photomultiplier feeding a single channel 
pulsecounter.
     The observations have been performed in our natural system
(lambda_eq^U= 3500+-300 A, lambda_eq^B= 4370+-450 A, lambda_eq^V= 5440+-300A) using HD 164898
(A0) as comparison star since it is only 31' far, and four other
stars of various spectral types and colours as standards for the
reduction to the UBV system. Among these standards we observed
the Winzer's comparison star HD 165358 = BS 6753 (A2V).

                       [FIGURE 1]

     From the first analysis of our observations the period
found by Winzer (1974) is confirmed, since we obtain a slightly
improved value of 0.517436d. In Fig. 1 the magnitude differences
HD 164429 - HD 164898 in the U light are plotted versus the
phase computed by the elements:
         JD_hel (U light max) - 2441450.86 +- 0.517436d*E.
Dots and crosses refer to the 1978 and 1979 observations, respectively; 
each point is an average of thirty single measurements.
The amplitude and the shape of our light curve are in good agreement 
with the Winzer's one.





               F.A. CATALANO, A. MAGAZZU and G. STRAZZULLA
               Osservatorio Astrofisico di Catania
               Istituto di Astronomia dell'Universita
               di Catania
               Citta Universitaria, Viale A. Doria
               I-95125-Catania-Italia





References :
Cowley, A.P., Cowley, C.R., Jaschek, M., Jaschek, C. 1969.,
      Astron. J. 74, 375 [BIBCODE 1969AJ.....74..375C ]
Winzer J., 1974, PhD. Thesis, University of Toronto [BIBCODE 1974PhDT........61W ]